Swift Combine 和 iOS 版本限制？

huangapple
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英文:

Swift Combine and iOS version limitations?

问题

以下是翻译好的部分：

例如，AppTrackingTransparency 在 iOS 14+ 中存在，但一个应用支持 iOS 13+。

我使用了以下代码：

  1. @available(iOS 14, *)
  2. func requestATTPermissions() -> Future<ATTrackingManager.AuthorizationStatus, Never> {
  3.     ...
  4. }
  6. if #available(iOS 14, *) {
  7.     requestATTPermissions()
  8.         .sink { [weak self] _ in
  9.             self?.completion?()
  10.         }
  11.         .store(in: &combineSubscriptionCollector.subscriptions)
  12. } else {
  13.     completion?()
  14. }

但是否可以将 if #available(iOS 14, *) { 移动到 Future/AnyPublisher 中，在 iOS 13 中工作方式类似于 Just(())，而在 iOS14+ 中请求 ATT？类似于以下方式：

  1. Just(()).map {
  2.     if #available(iOS 14, *) {
  3.         return requestATTPermissions()
  4.            .map { status in ... }
  5.     } else {
  6.         return Just(())
  7.     }
  8. }
  9. .sink { [weak self] _ in
  10.     self?.completion?()
  11. }
  12. .store(in: &combineSubscriptionCollector.subscriptions)
英文:

For example AppTrackingTransparency exists in iOS 14+ but an app supports iOS 13+.

I used the following code:

  1. @available(iOS 14, *)
  2.     func requestATTPermissions() -&gt;
  3.     Future&lt;ATTrackingManager.AuthorizationStatus, Never&gt; {
  4.     ...
  5. }
  7. if #available(iOS 14, *) {
  8.             requestATTPermissions()
  9.                 .sink { [weak self] _ in
  10.                     self?.completion?()
  11.                 }
  12.                 .store(in: &amp;combineSubscriptionCollector.subscriptions)
  13.         } else {
  14.             completion?()
  15.         }

But is it possible to move if #available(iOS 14, *) { into Future/AnyPublisher which in iOS 13 works like Just(()) and in iOS14+ requests ATT? Somehow like this:

  1. Just(()).map {
  2.   if #available(iOS 14, *) {
  3.     return requestATTPermissions()
  4.        .map { status in ... }
  5.   } else {
  6.     return Just(())
  7.   }
  8. }
  9. .sink { [weak self] _ in
  10.     self?.completion?()
  11. }
  12. .store(in: &amp;combineSubscriptionCollector.subscriptions)

答案1

得分: 1

If I understand correctly, you just need to use flatMap instead of map:

  1. Just(()).flatMap { _ in
  2.     if #available(iOS 14, *) {
  3.         return requestATTPermisions().map { status in
  4.             // 这里不需要返回任何内容...
  5.         }.eraseToAnyPublisher()
  6.     } else {
  7.         return Just(()).eraseToAnyPublisher()
  8.     }
  9. }
  10. // .sink and .store...

Though I think this is easier to read and understand:

  1. let publisher: AnyPublisher<(), Never>
  2. if #available(iOS 14, *) {
  3.     publisher = requestATTPermisions().map { status in
  4.         // ...
  5.     }.eraseToAnyPublisher()
  6. } else {
  7.     publisher = Just(()).eraseToAnyPublisher()
  8. }
  9. publisher.sink { ... }.store(in: ...)
英文:

If I understand correctly, you just need to use flatMap instead of map:

  1. Just(()).flatMap { _ in
  2.     if #available(iOS 14, *) {
  3.         return requestATTPermisions().map { status in
  4.             // do not return anything here...
  5.         }.eraseToAnyPublisher()
  6.     } else {
  7.         return Just(()).eraseToAnyPublisher()
  8.     }
  9. }
  10. // .sink and .store...

Though I think this is easier to read and understand:

  1. let publisher: AnyPublisher&lt;(), Never&gt;
  2. if #available(iOS 14, *) {
  3.     publisher = requestATTPermisions().map { status in
  4.         // ...
  5.     }.eraseToAnyPublisher()
  6. } else {
  7.     publisher = Just(()).eraseToAnyPublisher()
  8. }
  9. publisher.sink { ... }.store(in: ...)

huangapple
  • 本文由 发表于 2023年6月26日 16:33:18
  • 转载请务必保留本文链接：https://go.coder-hub.com/76554924.html
  • combine
  • ios
  • swift
  • version
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