mastodon-ios/Mastodon/Extension/UIControl.swift

65 lines
2.0 KiB
Swift

//
// UIControl.swift
// Mastodon
//
// Created by sxiaojian on 2021/3/8.
//
import Foundation
import UIKit
import Combine
/// A custom subscription to capture UIControl target events.
final class UIControlSubscription<SubscriberType: Subscriber, Control: UIControl>: Subscription where SubscriberType.Input == Control {
private var subscriber: SubscriberType?
private let control: Control
init(subscriber: SubscriberType, control: Control, event: UIControl.Event) {
self.subscriber = subscriber
self.control = control
control.addTarget(self, action: #selector(eventHandler), for: event)
}
func request(_ demand: Subscribers.Demand) {
// We do nothing here as we only want to send events when they occur.
// See, for more info: https://developer.apple.com/documentation/combine/subscribers/demand
}
func cancel() {
subscriber = nil
}
@objc private func eventHandler() {
_ = subscriber?.receive(control)
}
}
/// A custom `Publisher` to work with our custom `UIControlSubscription`.
struct UIControlPublisher<Control: UIControl>: Publisher {
typealias Output = Control
typealias Failure = Never
let control: Control
let controlEvents: UIControl.Event
init(control: Control, events: UIControl.Event) {
self.control = control
self.controlEvents = events
}
func receive<S>(subscriber: S) where S : Subscriber, S.Failure == UIControlPublisher.Failure, S.Input == UIControlPublisher.Output {
let subscription = UIControlSubscription(subscriber: subscriber, control: control, event: controlEvents)
subscriber.receive(subscription: subscription)
}
}
/// Extending the `UIControl` types to be able to produce a `UIControl.Event` publisher.
protocol CombineCompatible { }
extension UIControl: CombineCompatible { }
extension CombineCompatible where Self: UIControl {
func publisher(for events: UIControl.Event) -> UIControlPublisher<UIControl> {
return UIControlPublisher(control: self, events: events)
}
}