Merge pull request #66 from tootsuite/feature/navigationBarState

Feature/navigation bar state

Localization/app.json

@@ -169,10 +169,16 @@
             }
         },
         "home_timeline": {
-            "title": "Home"
+            "title": "Home",
+            "navigation_bar_state": {
+                "offline": "Offline",
+                "new_posts": "See new posts",
+                "published": "Published!",
+                "Publishing": "Publishing post..."
+            },
         },
         "public_timeline": {
             "title": "Public"
         }
     }
-}
+}

Mastodon.xcodeproj/project.pbxproj

@@ -49,6 +49,7 @@
 		2D42FF8F25C8228A004A627A /* UIButton.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D42FF8E25C8228A004A627A /* UIButton.swift */; };
 		2D45E5BF25C9549700A6D639 /* PublicTimelineViewModel+State.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D45E5BE25C9549700A6D639 /* PublicTimelineViewModel+State.swift */; };
 		2D46975E25C2A54100CF4AA9 /* NSLayoutConstraint.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D46975D25C2A54100CF4AA9 /* NSLayoutConstraint.swift */; };
+		2D571B2F26004EC000540450 /* NavigationBarProgressView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D571B2E26004EC000540450 /* NavigationBarProgressView.swift */; };
 		2D59819B25E4A581000FB903 /* MastodonConfirmEmailViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D59819A25E4A581000FB903 /* MastodonConfirmEmailViewController.swift */; };
 		2D5981A125E4A593000FB903 /* MastodonConfirmEmailViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D5981A025E4A593000FB903 /* MastodonConfirmEmailViewModel.swift */; };
 		2D5981BA25E4D7F8000FB903 /* ThirdPartyMailer in Frameworks */ = {isa = PBXBuildFile; productRef = 2D5981B925E4D7F8000FB903 /* ThirdPartyMailer */; };
@@ -72,6 +73,9 @@
 		2D7631B325C159F700929FB9 /* Item.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D7631B225C159F700929FB9 /* Item.swift */; };
 		2D82B9FF25E7863200E36F0F /* OnboardingViewControllerAppearance.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D82B9FE25E7863200E36F0F /* OnboardingViewControllerAppearance.swift */; };
 		2D82BA0525E7897700E36F0F /* MastodonResendEmailViewModelNavigationDelegateShim.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D82BA0425E7897700E36F0F /* MastodonResendEmailViewModelNavigationDelegateShim.swift */; };
+		2D8434F525FF465D00EECE90 /* HomeTimelineNavigationBarState.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D8434F425FF465D00EECE90 /* HomeTimelineNavigationBarState.swift */; };
+		2D8434FB25FF46B300EECE90 /* HomeTimelineNavigationBarView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D8434FA25FF46B300EECE90 /* HomeTimelineNavigationBarView.swift */; };
+		2D84350525FF858100EECE90 /* UIScrollView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D84350425FF858100EECE90 /* UIScrollView.swift */; };
 		2D927F0225C7E4F2004F19B8 /* Mention.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D927F0125C7E4F2004F19B8 /* Mention.swift */; };
 		2D927F0825C7E9A8004F19B8 /* Tag.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D927F0725C7E9A8004F19B8 /* Tag.swift */; };
 		2D927F0E25C7E9C9004F19B8 /* History.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2D927F0D25C7E9C9004F19B8 /* History.swift */; };
@@ -297,6 +301,7 @@
 		2D42FF8E25C8228A004A627A /* UIButton.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIButton.swift; sourceTree = "<group>"; };
 		2D45E5BE25C9549700A6D639 /* PublicTimelineViewModel+State.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "PublicTimelineViewModel+State.swift"; sourceTree = "<group>"; };
 		2D46975D25C2A54100CF4AA9 /* NSLayoutConstraint.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NSLayoutConstraint.swift; sourceTree = "<group>"; };
+		2D571B2E26004EC000540450 /* NavigationBarProgressView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NavigationBarProgressView.swift; sourceTree = "<group>"; };
 		2D59819A25E4A581000FB903 /* MastodonConfirmEmailViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MastodonConfirmEmailViewController.swift; sourceTree = "<group>"; };
 		2D5981A025E4A593000FB903 /* MastodonConfirmEmailViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MastodonConfirmEmailViewModel.swift; sourceTree = "<group>"; };
 		2D5A3D0225CF8742002347D6 /* ControlContainableScrollViews.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ControlContainableScrollViews.swift; sourceTree = "<group>"; };
@@ -318,6 +323,9 @@
 		2D7631B225C159F700929FB9 /* Item.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Item.swift; sourceTree = "<group>"; };
 		2D82B9FE25E7863200E36F0F /* OnboardingViewControllerAppearance.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OnboardingViewControllerAppearance.swift; sourceTree = "<group>"; };
 		2D82BA0425E7897700E36F0F /* MastodonResendEmailViewModelNavigationDelegateShim.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MastodonResendEmailViewModelNavigationDelegateShim.swift; sourceTree = "<group>"; };
+		2D8434F425FF465D00EECE90 /* HomeTimelineNavigationBarState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = HomeTimelineNavigationBarState.swift; sourceTree = "<group>"; };
+		2D8434FA25FF46B300EECE90 /* HomeTimelineNavigationBarView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = HomeTimelineNavigationBarView.swift; sourceTree = "<group>"; };
+		2D84350425FF858100EECE90 /* UIScrollView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIScrollView.swift; sourceTree = "<group>"; };
 		2D927F0125C7E4F2004F19B8 /* Mention.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Mention.swift; sourceTree = "<group>"; };
 		2D927F0725C7E9A8004F19B8 /* Tag.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Tag.swift; sourceTree = "<group>"; };
 		2D927F0D25C7E9C9004F19B8 /* History.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = History.swift; sourceTree = "<group>"; };
@@ -587,6 +595,7 @@
 			children = (
 				2D152A8B25C295CC009AA50C /* StatusView.swift */,
 				2D694A7325F9EB4E0038ADDC /* ContentWarningOverlayView.swift */,
+				2D571B2E26004EC000540450 /* NavigationBarProgressView.swift */,
 			);
 			path = Content;
 			sourceTree = "<group>";
@@ -612,6 +621,8 @@
 				2D38F1EA25CD477000561493 /* HomeTimelineViewModel+LoadLatestState.swift */,
 				2D38F1F025CD477D00561493 /* HomeTimelineViewModel+LoadMiddleState.swift */,
 				2D38F1F625CD47AC00561493 /* HomeTimelineViewModel+LoadOldestState.swift */,
+				2D8434F425FF465D00EECE90 /* HomeTimelineNavigationBarState.swift */,
+				2D8434FA25FF46B300EECE90 /* HomeTimelineNavigationBarView.swift */,
 			);
 			path = HomeTimeline;
 			sourceTree = "<group>";
@@ -1139,6 +1150,7 @@
 				2D206B9125F60EA700143C56 /* UIControl.swift */,
 				5DF1056325F887CB00D6C0D4 /* AVPlayer.swift */,
 				DB47229625F9EFAD00DA7F53 /* NSManagedObjectContext.swift */,
+				2D84350425FF858100EECE90 /* UIScrollView.swift */,
 			);
 			path = Extension;
 			sourceTree = "<group>";
@@ -1596,6 +1608,7 @@
 				2D5A3D3825CF8D9F002347D6 /* ScrollViewContainer.swift in Sources */,
 				DB1E347825F519300079D7DF /* PickServerItem.swift in Sources */,
 				DB1FD45A25F27898004CFCFC /* CategoryPickerItem.swift in Sources */,
+				2D571B2F26004EC000540450 /* NavigationBarProgressView.swift in Sources */,
 				0FAA101225E105390017CCDE /* PrimaryActionButton.swift in Sources */,
 				DB8AF53025C13561002E6C99 /* AppContext.swift in Sources */,
 				DB92CF7225E7BB98002C1017 /* PollOptionTableViewCell.swift in Sources */,
@@ -1603,7 +1616,9 @@
 				2D364F7225E66D7500204FDC /* MastodonResendEmailViewController.swift in Sources */,
 				2D38F1F125CD477D00561493 /* HomeTimelineViewModel+LoadMiddleState.swift in Sources */,
 				DB68A06325E905E000CFDF14 /* UIApplication.swift in Sources */,
+				2D8434FB25FF46B300EECE90 /* HomeTimelineNavigationBarView.swift in Sources */,
 				DB45FAD725CA6C76005A8AC7 /* UIBarButtonItem.swift in Sources */,
+				2D8434F525FF465D00EECE90 /* HomeTimelineNavigationBarState.swift in Sources */,
 				2D152A8C25C295CC009AA50C /* StatusView.swift in Sources */,
 				2D42FF8525C8224F004A627A /* HitTestExpandedButton.swift in Sources */,
 				DB72601C25E36A2100235243 /* MastodonServerRulesViewController.swift in Sources */,
@@ -1638,6 +1653,7 @@
 				2D82B9FF25E7863200E36F0F /* OnboardingViewControllerAppearance.swift in Sources */,
 				5DF1054725F8870E00D6C0D4 /* VideoPlayerViewModel.swift in Sources */,
 				2D38F1E525CD46C100561493 /* HomeTimelineViewModel.swift in Sources */,
+				2D84350525FF858100EECE90 /* UIScrollView.swift in Sources */,
 				2D76316B25C14D4C00929FB9 /* PublicTimelineViewModel.swift in Sources */,
 				2DA6055125F74407006356F9 /* AudioContainerViewModel.swift in Sources */,
 				0FB3D2FE25E4CB6400AAD544 /* PickServerTitleCell.swift in Sources */,

Mastodon/Extension/UIScrollView.swift

@@ -0,0 +1,32 @@
+//
+//  UIScrollView.swift
+//  Mastodon
+//
+//  Created by sxiaojian on 2021/3/15.
+//
+
+import UIKit
+
+extension UIScrollView {
+    public enum ScrollDirection {
+        case top
+        case bottom
+        case left
+        case right
+    }
+
+    public func scroll(to direction: ScrollDirection, animated: Bool) {
+        let offset: CGPoint
+        switch direction {
+        case .top:
+            offset = CGPoint(x: contentOffset.x, y: -adjustedContentInset.top)
+        case .bottom:
+            offset = CGPoint(x: contentOffset.x, y: max(-adjustedContentInset.top, contentSize.height - frame.height + adjustedContentInset.bottom))
+        case .left:
+            offset = CGPoint(x: -adjustedContentInset.left, y: contentOffset.y)
+        case .right:
+            offset = CGPoint(x: max(-adjustedContentInset.left, contentSize.width - frame.width + adjustedContentInset.right), y: contentOffset.y)
+        }
+        setContentOffset(offset, animated: animated)
+    }
+}

Mastodon/Generated/Assets.swift

@@ -67,6 +67,10 @@ internal enum Asset {
       internal static let invalid = ColorAsset(name: "Colors/TextField/invalid")
       internal static let valid = ColorAsset(name: "Colors/TextField/valid")
     }
+    internal static let backgroundLight = ColorAsset(name: "Colors/backgroundLight")
+    internal static let buttonDefault = ColorAsset(name: "Colors/buttonDefault")
+    internal static let buttonDisabled = ColorAsset(name: "Colors/buttonDisabled")
+    internal static let buttonInactive = ColorAsset(name: "Colors/buttonInactive")
     internal static let lightAlertYellow = ColorAsset(name: "Colors/lightAlertYellow")
     internal static let lightBackground = ColorAsset(name: "Colors/lightBackground")
     internal static let lightBrandBlue = ColorAsset(name: "Colors/lightBrandBlue")

Mastodon/Generated/Strings.swift

@@ -162,6 +162,16 @@ internal enum L10n {
     internal enum HomeTimeline {
       /// Home
       internal static let title = L10n.tr("Localizable", "Scene.HomeTimeline.Title")
+      internal enum NavigationBarState {
+        /// See new posts
+        internal static let newPosts = L10n.tr("Localizable", "Scene.HomeTimeline.NavigationBarState.NewPosts")
+        /// Offline
+        internal static let offline = L10n.tr("Localizable", "Scene.HomeTimeline.NavigationBarState.Offline")
+        /// Published!
+        internal static let published = L10n.tr("Localizable", "Scene.HomeTimeline.NavigationBarState.Published")
+        /// Publishing post...
+        internal static let publishing = L10n.tr("Localizable", "Scene.HomeTimeline.NavigationBarState.Publishing")
+      }
     }
     internal enum PublicTimeline {
       /// Public

Mastodon/Resources/Assets.xcassets/Colors/backgroundLight.colorset/Contents.json

@@ -0,0 +1,20 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.910",
+          "green" : "0.882",
+          "red" : "0.851"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Mastodon/Resources/Assets.xcassets/Colors/buttonDefault.colorset/Contents.json

@@ -0,0 +1,20 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.851",
+          "green" : "0.565",
+          "red" : "0.169"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Mastodon/Resources/Assets.xcassets/Colors/buttonDisabled.colorset/Contents.json

@@ -0,0 +1,20 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.784",
+          "green" : "0.682",
+          "red" : "0.608"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Mastodon/Resources/Assets.xcassets/Colors/buttonInactive.colorset/Contents.json

@@ -0,0 +1,20 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.549",
+          "green" : "0.510",
+          "red" : "0.431"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Mastodon/Resources/Assets.xcassets/Colors/lightAlertYellow.colorset/Contents.json

@@ -1,20 +1,20 @@
 {
   "colors" : [
     {
+      "idiom" : "universal",
       "color" : {
         "color-space" : "srgb",
         "components" : {
-          "alpha" : "1.000",
+          "red" : "0.792",
           "blue" : "0.016",
           "green" : "0.561",
-          "red" : "0.792"
+          "alpha" : "1.000"
         }
-      },
+      }
-      "idiom" : "universal"
     }
   ],
   "info" : {
-    "author" : "xcode",
+    "version" : 1,
-    "version" : 1
+    "author" : "xcode"
   }
-}
+}

Mastodon/Resources/Assets.xcassets/Colors/lightDangerRed.colorset/Contents.json

@@ -1,20 +1,20 @@
 {
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  },
   "colors" : [
     {
       "color" : {
         "color-space" : "srgb",
         "components" : {
           "alpha" : "1.000",
+          "red" : "0.875",
           "blue" : "0.353",
-          "green" : "0.251",
+          "green" : "0.251"
-          "red" : "0.875"
         }
       },
       "idiom" : "universal"
     }
-  ],
+  ]
-  "info" : {
+}
-    "author" : "xcode",
-    "version" : 1
-  }
-}

Mastodon/Resources/Assets.xcassets/Colors/lightDarkGray.colorset/Contents.json

@@ -1,6 +1,11 @@
 {
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  },
   "colors" : [
     {
+      "idiom" : "universal",
       "color" : {
         "color-space" : "srgb",
         "components" : {
@@ -9,12 +14,7 @@
           "green" : "0.137",
           "red" : "0.122"
         }
-      },
+      }
-      "idiom" : "universal"
     }
-  ],
+  ]
-  "info" : {
+}
-    "author" : "xcode",
-    "version" : 1
-  }
-}

Mastodon/Resources/Assets.xcassets/Colors/lightSecondaryText.colorset/Contents.json

@@ -1,20 +1,20 @@
 {
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  },
   "colors" : [
     {
+      "idiom" : "universal",
       "color" : {
-        "color-space" : "srgb",
         "components" : {
+          "blue" : "0.263",
+          "green" : "0.235",
           "alpha" : "0.600",
-          "blue" : "67",
+          "red" : "0.235"
-          "green" : "60",
+        },
-          "red" : "60"
+        "color-space" : "srgb"
-        }
+      }
-      },
-      "idiom" : "universal"
     }
-  ],
+  ]
-  "info" : {
+}
-    "author" : "xcode",
-    "version" : 1
-  }
-}

Mastodon/Resources/Assets.xcassets/Colors/lightSuccessGreen.colorset/Contents.json

@@ -1,20 +1,20 @@
 {
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  },
   "colors" : [
     {
+      "idiom" : "universal",
       "color" : {
         "color-space" : "srgb",
         "components" : {
           "alpha" : "1.000",
-          "blue" : "0.604",
           "green" : "0.741",
-          "red" : "0.475"
+          "red" : "0.475",
+          "blue" : "0.604"
         }
-      },
+      }
-      "idiom" : "universal"
     }
-  ],
+  ]
-  "info" : {
+}
-    "author" : "xcode",
-    "version" : 1
-  }
-}

Mastodon/Resources/Assets.xcassets/Colors/lightWhite.colorset/Contents.json

@@ -1,20 +1,20 @@
 {
   "colors" : [
     {
+      "idiom" : "universal",
       "color" : {
-        "color-space" : "srgb",
         "components" : {
+          "red" : "0.996",
           "alpha" : "1.000",
           "blue" : "0.996",
-          "green" : "1.000",
+          "green" : "1.000"
-          "red" : "0.996"
+        },
-        }
+        "color-space" : "srgb"
-      },
+      }
-      "idiom" : "universal"
     }
   ],
   "info" : {
-    "author" : "xcode",
+    "version" : 1,
-    "version" : 1
+    "author" : "xcode"
   }
-}
+}

Mastodon/Resources/en.lproj/Localizable.strings

@@ -46,6 +46,10 @@
 "Scene.ConfirmEmail.Subtitle" = "We just sent an email to %@,
 tap the link to confirm your account.";
 "Scene.ConfirmEmail.Title" = "One last thing.";
+"Scene.HomeTimeline.NavigationBarState.NewPosts" = "See new posts";
+"Scene.HomeTimeline.NavigationBarState.Offline" = "Offline";
+"Scene.HomeTimeline.NavigationBarState.Published" = "Published!";
+"Scene.HomeTimeline.NavigationBarState.Publishing" = "Publishing post...";
 "Scene.HomeTimeline.Title" = "Home";
 "Scene.PublicTimeline.Title" = "Public";
 "Scene.Register.Error.Item.Agreement" = "Agreement";
@@ -92,4 +96,4 @@ any server.";
 "Scene.ServerRules.Subtitle" = "These rules are set by the admins of %@.";
 "Scene.ServerRules.Title" = "Some ground rules.";
 "Scene.Welcome.Slogan" = "Social networking
-back in your hands.";
+back in your hands.";

Mastodon/Scene/HomeTimeline/HomeTimelineNavigationBarState.swift

@@ -0,0 +1,156 @@
+//
+//  HomeTimelineNavigationBarState.swift
+//  Mastodon
+//
+//  Created by sxiaojian on 2021/3/15.
+//
+
+import Combine
+import Foundation
+import UIKit
+
+final class HomeTimelineNavigationBarState {
+    static let errorCountMax: Int = 3
+    var disposeBag = Set<AnyCancellable>()
+    var errorCountDownDispose: AnyCancellable?
+    var timerDispose: AnyCancellable?
+    var networkErrorCountSubject = PassthroughSubject<Bool, Never>()
+    
+    var newTopContent = CurrentValueSubject<Bool, Never>(false)
+    var hasContentBeforeFetching: Bool = true
+    
+    weak var viewController: HomeTimelineViewController?
+    
+    let timestampUpdatePublisher = Timer.publish(every: NavigationBarProgressView.progressAnimationDuration, on: .main, in: .common)
+        .autoconnect()
+        .share()
+        .eraseToAnyPublisher()
+    
+    init() {
+        reCountdown()
+        subscribeNewContent()
+        addGesture()
+    }
+}
+
+extension HomeTimelineNavigationBarState {
+    func showOfflineInNavigationBar() {
+        HomeTimelineNavigationBarView.progressView.removeFromSuperview()
+        viewController?.navigationItem.titleView = HomeTimelineNavigationBarView.offlineView
+    }
+    
+    func showNewPostsInNavigationBar() {
+        HomeTimelineNavigationBarView.progressView.removeFromSuperview()
+        viewController?.navigationItem.titleView = HomeTimelineNavigationBarView.newPostsView
+    }
+    
+    func showPublishingNewPostInNavigationBar() {
+        let progressView = HomeTimelineNavigationBarView.progressView
+        if let navigationBar = viewController?.navigationBar(), progressView.superview == nil {
+            navigationBar.addSubview(progressView)
+            NSLayoutConstraint.activate([
+                progressView.bottomAnchor.constraint(equalTo: navigationBar.bottomAnchor),
+                progressView.leadingAnchor.constraint(equalTo: navigationBar.leadingAnchor),
+                progressView.trailingAnchor.constraint(equalTo: navigationBar.trailingAnchor),
+                progressView.heightAnchor.constraint(equalToConstant: 3)
+            ])
+        }
+        progressView.layoutIfNeeded()
+        progressView.progress = 0
+        viewController?.navigationItem.titleView = HomeTimelineNavigationBarView.publishingLabel
+        
+        var times: Int = 0
+        timerDispose = timestampUpdatePublisher
+            .map { _ in
+                times += 1
+                return Double(times)
+            }
+            .scan(0) { value, count in
+                value + 1 / pow(Double(2), count)
+            }
+            .receive(on: DispatchQueue.main)
+            .sink { value in
+                print(value)
+                progressView.progress = CGFloat(value)
+            }
+    }
+    
+    func showPublishedInNavigationBar() {
+        timerDispose = nil
+        HomeTimelineNavigationBarView.progressView.removeFromSuperview()
+        viewController?.navigationItem.titleView = HomeTimelineNavigationBarView.publishedView
+        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 3) {
+            self.showMastodonLogoInNavigationBar()
+        }
+    }
+    
+    func showMastodonLogoInNavigationBar() {
+        HomeTimelineNavigationBarView.progressView.removeFromSuperview()
+        viewController?.navigationItem.titleView = HomeTimelineNavigationBarView.mastodonLogoTitleView
+    }
+}
+
+extension HomeTimelineNavigationBarState {
+    func handleScrollViewDidScroll(_ scrollView: UIScrollView) {
+        let contentOffsetY = scrollView.contentOffset.y
+        let isShowingNewPostsNew = viewController?.navigationItem.titleView === HomeTimelineNavigationBarView.newPostsView
+        if !isShowingNewPostsNew {
+            return
+        }
+        let isTop = contentOffsetY < -scrollView.contentInset.top
+        if isTop {
+            newTopContent.value = false
+            showMastodonLogoInNavigationBar()
+        }
+    }
+    
+    func addGesture() {
+        let tapGesture = UITapGestureRecognizer.singleTapGestureRecognizer
+        tapGesture.addTarget(self, action: #selector(HomeTimelineNavigationBarState.newPostsNewDidPressed(_:)))
+        HomeTimelineNavigationBarView.newPostsView.addGestureRecognizer(tapGesture)
+    }
+    
+    @objc func newPostsNewDidPressed(_ sender: UITapGestureRecognizer) {
+        if newTopContent.value == true {
+            viewController?.tableView.scrollToRow(at: IndexPath(row: 0, section: 0), at: .top, animated: true)
+        }
+    }
+}
+
+extension HomeTimelineNavigationBarState {
+    func subscribeNewContent() {
+        newTopContent
+            .receive(on: DispatchQueue.main)
+            .sink { [weak self] newContent in
+                guard let self = self else { return }
+                if self.hasContentBeforeFetching, newContent {
+                    self.showNewPostsInNavigationBar()
+                }
+            }
+            .store(in: &disposeBag)
+    }
+
+    func reCountdown() {
+        errorCountDownDispose = networkErrorCountSubject
+            .scan(0) { value, _ in value + 1 }
+            .sink(receiveValue: { [weak self] errorCount in
+                guard let self = self else { return }
+                if errorCount >= HomeTimelineNavigationBarState.errorCountMax {
+                    self.showOfflineInNavigationBar()
+                }
+            })
+    }
+    
+    func receiveCompletion(completion: Subscribers.Completion<Error>) {
+        switch completion {
+        case .failure:
+            networkErrorCountSubject.send(false)
+        case .finished:
+            reCountdown()
+            let isShowingOfflineView = viewController?.navigationItem.titleView === HomeTimelineNavigationBarView.offlineView
+            if isShowingOfflineView {
+                showMastodonLogoInNavigationBar()
+            }
+        }
+    }
+}

Mastodon/Scene/HomeTimeline/HomeTimelineNavigationBarView.swift

@@ -0,0 +1,80 @@
+//
+//  HomeTimelineNavigationBarView.swift
+//  Mastodon
+//
+//  Created by sxiaojian on 2021/3/15.
+//
+
+import UIKit
+
+final class HomeTimelineNavigationBarView {
+    static let mastodonLogoTitleView: UIImageView = {
+        let imageView = UIImageView(image: Asset.Asset.mastodonTextLogo.image.withRenderingMode(.alwaysTemplate))
+        imageView.tintColor = Asset.Colors.Label.primary.color
+        return imageView
+    }()
+    
+    static let offlineView: UIView = {
+        let view = HomeTimelineNavigationBarView.backgroundViewWithColor(color: Asset.Colors.lightDangerRed.color)
+        let label = HomeTimelineNavigationBarView.contentLabel(text: L10n.Scene.HomeTimeline.NavigationBarState.offline)
+        HomeTimelineNavigationBarView.addLabelToView(label: label, view: view)
+        return view
+    }()
+    
+    static let newPostsView: UIView = {
+        let view = HomeTimelineNavigationBarView.backgroundViewWithColor(color: Asset.Colors.Button.highlight.color)
+        let label = HomeTimelineNavigationBarView.contentLabel(text: L10n.Scene.HomeTimeline.NavigationBarState.newPosts)
+        HomeTimelineNavigationBarView.addLabelToView(label: label, view: view)
+        return view
+    }()
+    
+    static var publishedView: UIView = {
+        let view = HomeTimelineNavigationBarView.backgroundViewWithColor(color: Asset.Colors.lightSuccessGreen.color)
+        let label = HomeTimelineNavigationBarView.contentLabel(text: L10n.Scene.HomeTimeline.NavigationBarState.published)
+        HomeTimelineNavigationBarView.addLabelToView(label: label, view: view)
+        return view
+    }()
+    
+    static var progressView: NavigationBarProgressView = {
+        let view = NavigationBarProgressView()
+        return view
+    }()
+    
+    static var publishingLabel: UILabel = {
+        let label = UILabel()
+        label.translatesAutoresizingMaskIntoConstraints = false
+        label.textColor = .black
+        label.font = UIFontMetrics(forTextStyle: .headline).scaledFont(for: .systemFont(ofSize: 17, weight: .semibold))
+        label.text = L10n.Scene.HomeTimeline.NavigationBarState.publishing
+        return label
+    }()
+    
+    static func addLabelToView(label: UILabel, view: UIView) {
+        view.addSubview(label)
+        NSLayoutConstraint.activate([
+            label.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 16),
+            view.trailingAnchor.constraint(equalTo: label.trailingAnchor, constant: 16),
+            label.topAnchor.constraint(equalTo: view.topAnchor, constant: 1),
+            view.bottomAnchor.constraint(equalTo: label.bottomAnchor, constant: 1),
+            view.heightAnchor.constraint(equalToConstant: 24),
+        ])
+    }
+    
+    static func backgroundViewWithColor(color: UIColor) -> UIView {
+        let view = UIView()
+        view.backgroundColor = color
+        view.translatesAutoresizingMaskIntoConstraints = false
+        view.layer.cornerRadius = 12
+        view.clipsToBounds = true
+        return view
+    }
+    
+    static func contentLabel(text: String) -> UILabel {
+        let label = UILabel()
+        label.translatesAutoresizingMaskIntoConstraints = false
+        label.textColor = .white
+        label.font = UIFontMetrics(forTextStyle: .headline).scaledFont(for: .systemFont(ofSize: 15, weight: .bold))
+        label.text = text
+        return label
+    }
+}

Mastodon/Scene/HomeTimeline/HomeTimelineViewController.swift

@@ -64,11 +64,7 @@ extension HomeTimelineViewController {
         
         title = L10n.Scene.HomeTimeline.title
         view.backgroundColor = Asset.Colors.Background.systemGroupedBackground.color
-        navigationItem.titleView = {
+        navigationItem.titleView = HomeTimelineNavigationBarView.mastodonLogoTitleView
-            let imageView = UIImageView(image: Asset.Asset.mastodonTextLogo.image.withRenderingMode(.alwaysTemplate))
-            imageView.tintColor = Asset.Colors.Label.primary.color
-            return imageView
-        }()
         navigationItem.leftBarButtonItem = settingBarButtonItem
         #if DEBUG
         // long press to trigger debug menu
@@ -101,6 +97,7 @@ extension HomeTimelineViewController {
         ])
 
         viewModel.tableView = tableView
+        viewModel.viewController = self
         viewModel.contentOffsetAdjustableTimelineViewControllerDelegate = self
         tableView.delegate = self
         viewModel.setupDiffableDataSource(
@@ -208,6 +205,7 @@ extension HomeTimelineViewController {
 extension HomeTimelineViewController {
     func scrollViewDidScroll(_ scrollView: UIScrollView) {
         handleScrollViewDidScroll(scrollView)
+        self.viewModel.homeTimelineNavigationBarState.handleScrollViewDidScroll(scrollView)
     }
 }
 

Mastodon/Scene/HomeTimeline/HomeTimelineViewModel+LoadLatestState.swift

@@ -73,6 +73,7 @@ extension HomeTimelineViewModel.LoadLatestState {
                     stateMachine.enter(Fail.self)
                     return
                 }
+                viewModel.homeTimelineNavigationBarState.hasContentBeforeFetching = !latestTootIDs.isEmpty
                 let end = CACurrentMediaTime()
                 os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s: collect toots id cost: %.2fs", ((#file as NSString).lastPathComponent), #line, #function, end - start)
                 
@@ -80,6 +81,7 @@ extension HomeTimelineViewModel.LoadLatestState {
                 viewModel.context.apiService.homeTimeline(domain: activeMastodonAuthenticationBox.domain, authorizationBox: activeMastodonAuthenticationBox)
                     .receive(on: DispatchQueue.main)
                     .sink { completion in
+                        viewModel.homeTimelineNavigationBarState.receiveCompletion(completion: completion)
                         switch completion {
                         case .failure(let error):
                             // TODO: handle error
@@ -97,9 +99,12 @@ extension HomeTimelineViewModel.LoadLatestState {
                         let toots = response.value
                         let newToots = toots.filter { !latestTootIDs.contains($0.id) }
                         os_log("%{public}s[%{public}ld], %{public}s: load %{public}ld new toots", ((#file as NSString).lastPathComponent), #line, #function, newToots.count)
-
+                        
                         if newToots.isEmpty {
                             viewModel.isFetchingLatestTimeline.value = false
+                            viewModel.homeTimelineNavigationBarState.newTopContent.value = false
+                        } else {
+                            viewModel.homeTimelineNavigationBarState.newTopContent.value = true
                         }
                     }
                     .store(in: &viewModel.disposeBag)

Mastodon/Scene/HomeTimeline/HomeTimelineViewModel+LoadMiddleState.swift

@@ -68,6 +68,7 @@ extension HomeTimelineViewModel.LoadMiddleState {
                 .delay(for: .seconds(1), scheduler: DispatchQueue.main)
                 .receive(on: DispatchQueue.main)
                 .sink { completion in
+                    viewModel.homeTimelineNavigationBarState.receiveCompletion(completion: completion)
                     switch completion {
                     case .failure(let error):
                         // TODO: handle error

Mastodon/Scene/HomeTimeline/HomeTimelineViewModel+LoadOldestState.swift

@@ -58,6 +58,7 @@ extension HomeTimelineViewModel.LoadOldestState {
                 .delay(for: .seconds(1), scheduler: DispatchQueue.main)
                 .receive(on: DispatchQueue.main)
                 .sink { completion in
+                    viewModel.homeTimelineNavigationBarState.receiveCompletion(completion: completion)
                     switch completion {
                     case .failure(let error):
                         os_log("%{public}s[%{public}ld], %{public}s: fetch toots failed. %s", ((#file as NSString).lastPathComponent), #line, #function, error.localizedDescription)

Mastodon/Scene/HomeTimeline/HomeTimelineViewModel.swift

@@ -29,9 +29,16 @@ final class HomeTimelineViewModel: NSObject {
     let isFetchingLatestTimeline = CurrentValueSubject<Bool, Never>(false)
     let viewDidAppear = PassthroughSubject<Void, Never>()
     
+    let homeTimelineNavigationBarState = HomeTimelineNavigationBarState()
+    
     weak var contentOffsetAdjustableTimelineViewControllerDelegate: ContentOffsetAdjustableTimelineViewControllerDelegate?
     weak var tableView: UITableView?
     weak var timelineMiddleLoaderTableViewCellDelegate: TimelineMiddleLoaderTableViewCellDelegate?
+    weak var viewController: HomeTimelineViewController? {
+        willSet(value) {
+            self.homeTimelineNavigationBarState.viewController = value
+        }
+    }
     
     // output
     // top loader

Mastodon/Scene/Share/View/Content/NavigationBarProgressView.swift

@@ -0,0 +1,56 @@
+//
+//  NavigationBarProgressView.swift
+//  Mastodon
+//
+//  Created by sxiaojian on 2021/3/16.
+//
+
+import UIKit
+
+class NavigationBarProgressView: UIView {
+    
+    static let progressAnimationDuration: TimeInterval = 0.3
+    
+    let sliderView: UIView = {
+        let view = UIView()
+        view.backgroundColor = Asset.Colors.buttonDefault.color
+        view.translatesAutoresizingMaskIntoConstraints = false
+        return view
+    }()
+    
+    var sliderTrailingAnchor: NSLayoutConstraint!
+    
+    var progress: CGFloat = 0 {
+        willSet(value) {
+            sliderTrailingAnchor.constant = (1 - progress) * bounds.width
+            UIView.animate(withDuration: NavigationBarProgressView.progressAnimationDuration) {
+                self.setNeedsLayout()
+            }
+        }
+    }
+    
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+        _init()
+    }
+    
+    required init?(coder: NSCoder) {
+        super.init(coder: coder)
+        _init()
+    }
+}
+
+extension NavigationBarProgressView {
+    func _init() {
+        self.translatesAutoresizingMaskIntoConstraints = false
+        self.backgroundColor = .clear
+        addSubview(sliderView)
+        sliderTrailingAnchor = trailingAnchor.constraint(equalTo: sliderView.trailingAnchor)
+        NSLayoutConstraint.activate([
+            sliderView.topAnchor.constraint(equalTo: topAnchor),
+            sliderView.leadingAnchor.constraint(equalTo: leadingAnchor),
+            sliderView.bottomAnchor.constraint(equalTo: bottomAnchor),
+            sliderTrailingAnchor
+        ])
+    }
+}