chore: set the photoButton highlight with some value alpha

Mastodon/Scene/Onboarding/Register/MastodonRegisterViewController.swift

@@ -8,9 +8,9 @@
 import Combine
 import MastodonSDK
 import os.log
+import PhotosUI
 import UIKit
 import UITextField_Shake
-import PhotosUI
 
 final class MastodonRegisterViewController: UIViewController, NeedsDependency, OnboardingViewControllerAppearance {
     var disposeBag = Set<AnyCancellable>()
@@ -216,19 +216,28 @@ final class MastodonRegisterViewController: UIViewController, NeedsDependency, O
     }()
     
     deinit {
-        os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s", ((#file as NSString).lastPathComponent), #line, #function)
+        os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s", (#file as NSString).lastPathComponent, #line, #function)
     }
-    
 }
 
 extension MastodonRegisterViewController {
-    
     override func viewDidLoad() {
         super.viewDidLoad()
         
         setupOnboardingAppearance()
         defer { setupNavigationBarBackgroundView() }
         
+        NSObject.KeyValueObservingPublisher<UIButton, Bool>(object: photoButton, keyPath: \.isHighlighted, options: NSKeyValueObservingOptions.new)
+            .receive(on: DispatchQueue.main)
+            .sink { [weak self] isHighlighted in
+                guard let self = self else { return }
+                let alpha: CGFloat = isHighlighted ? 0.8 : 1
+                self.plusIcon.alpha = alpha
+                self.plusIconBackground.alpha = alpha
+                self.photoButton.alpha = alpha
+            }
+            .store(in: &disposeBag)
+        
         domainLabel.text = "@" + viewModel.domain + "  "
         domainLabel.sizeToFit()
         passwordCheckLabel.attributedText = viewModel.attributeStringForPassword()
@@ -492,10 +501,9 @@ extension MastodonRegisterViewController {
             .store(in: &disposeBag)
 
         if viewModel.approvalRequired {
-            
             inviteTextField.delegate = self
             NSLayoutConstraint.activate([
-                inviteTextField.heightAnchor.constraint(equalToConstant: 50).priority(.defaultHigh)
+                inviteTextField.heightAnchor.constraint(equalToConstant: 50).priority(.defaultHigh),
             ])
             
             viewModel.inviteValidateState
@@ -503,7 +511,6 @@ extension MastodonRegisterViewController {
                 .sink { [weak self] validateState in
                     guard let self = self else { return }
                     self.setTextFieldValidAppearance(self.inviteTextField, validateState: validateState)
-
                 }
                 .store(in: &disposeBag)
             NotificationCenter.default
@@ -518,11 +525,9 @@ extension MastodonRegisterViewController {
         
         signUpButton.addTarget(self, action: #selector(MastodonRegisterViewController.signUpButtonPressed(_:)), for: .touchUpInside)
     }
-    
 }
 
 extension MastodonRegisterViewController: UITextFieldDelegate {
-    
     func textFieldDidBeginEditing(_ textField: UITextField) {
         let text = textField.text?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
         
@@ -564,7 +569,6 @@ extension MastodonRegisterViewController: UITextFieldDelegate {
 }
 
 extension MastodonRegisterViewController {
-    
     @objc private func tapGestureRecognizerHandler(_ sender: UITapGestureRecognizer) {
         view.endEditing(true)
     }
@@ -611,6 +615,5 @@ extension MastodonRegisterViewController {
             self.coordinator.present(scene: .mastodonConfirmEmail(viewModel: viewModel), from: self, transition: .show)
         }
         .store(in: &disposeBag)
-        
     }
 }