ios - 为什么 uiimagePickerController.mediaTypes = [kUTTypeMovie as String] 包括 Live Photos 作为 Bounce 或 Loop Effect 作为 Video？

Question

我使用 UIImagePicker 仅从我的库中选择视频，并将我的媒体类型设置为:

imagePicker.mediaTypes = [kUTTypeMovie as String]

我注意到，当展示库时，即使我只希望看到视频，如果库中有一张带有 Bounce 或 Loop 效果的实时照片，它也出现了。如果我拍摄同一张照片并将其效果切换为 Live 或 Long Exposure，它将不再显示在图库中。如果我将它切换回 Bounce 或 Loop 它会重新出现。

我已经尝试了 .photoLibrary 和 .savedPhotosAlbum 并且发生了同样的事情。

我问的原因是因为我想让他们远离图书馆，我只想选择 xxx 秒或更长时间的视频。

1. 即使我只选择视频，为什么这些效果类型会出现在图像选择器库中？
2. 为什么只有Loop和Bounce出现，而Long Exposure和Live没有出现？
3. 如何将它们拒之门外？

也许这是一个单独的问题，但由于它属于相同的 Live 和 Bounce 照片问题，所以我添加了它。我注意到，如果我将源自 Live 或 Bounce 照片的 url 放入 AVPlayer 中，如果我进入后台并返回，当该应用程序回到前台，它只发生在这 2 个效果(不应该可用)。当应用程序进入后台时，我使用此方法正确删除了 AVPlayerLayer Remove AVPlayerLayer但是当在播放器中初始化来自那些影响类型的 url 时，它仍然在前台短暂地卡住(应用程序没有响应)。

代码:

import MobileCoreServices
import AVFoundation

class ViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate{

var playerItem: AVPlayerItem?
var player: AVPlayer?
var playerLayer: AVPlayerLayer?
var currentPlayTime: CMTime?
let imagePicker = UIImagePickerController()

override func viewDidLoad() {
    super.viewDidLoad()

    imagePickerController.delegate = self

    NotificationCenter.default.addObserver(self, selector: #selector(appHasEnteredBackground), name: Notification.Name.UIApplicationWillResignActive, object: nil)

    NotificationCenter.default.addObserver(self, selector: #selector(appWillEnterForeground), name: Notification.Name.UIApplicationWillEnterForeground, object: nil)
}

override func viewDidLayoutSubviews() {
    // I have a UIView Outlet for the AVPlayerLayer named viewForPlayerLayer.

    guard let playerLayer = playerLayer else { return }
    playerLayer.videoGravity = .resizeAspectFill
    viewForPlayerLayer.layer.insertSublayer(playerLayer, at: 0)
    playerLayer.frame = viewForPlayerLayer.bounds
    playerLayer.masksToBounds = true

}

@IBAction fileprivate func showLibraryButtonTapped(_ sender: UIButton) {

    imagePicker.sourceType = UIImagePickerControllerSourceType.photoLibrary // .savedPhotosAlbum also tried 
    imagePicker.mediaTypes = [kUTTypeMovie as String]
    imagePicker.videoMaximumDuration = 60
    present(imagePicker, animated: true, completion: nil)
}

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

    if let url = info[UIImagePickerControllerMediaURL] as? URL{

          let asset = AVAsset(url: url)
          playerItem = AVPlayerItem(asset: asset)
          player = AVPlayer(playerItem: playerItem!)
          playerLayer = AVPlayerLayer(player: player)
          player?.play()
    }
    imagePicker.dismiss(animated: true, completion: nil)
}

func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
    imagePicker.dismiss(animated: true, completion: nil)
}

@objc fileprivate func appHasEnteredBackground() {

    currentPlayTime = player.currentTime()

    if player.isPlaying{
        player.pause()
    }

    playerLayer = nil
}

@objc fileprivate func appWillEnterForeground(){

    if let player = player, let currentPlayTime = currentPlayTime{

        playerLayer = AVPlayerLayer(player: player)

        player.seek(to: currentPlayTime, toleranceBefore: kCMTimeZero, toleranceAfter: kCMTimeZero)
    }
}

}

Answer 1

如果您要求显示视频，则无法阻止循环/反弹实时照片视频出现在选取器中，因为它们是视频。但是，如果用户在委托(delegate)方法中选择 一个，您可以检测到一个。为此，UIImagePickerControllerMediaType 不够精细。相反，获取照片库授权并获取由 UIImagePickerControllerPHAsset 键返回的 PHAsset，并检查其 playbackStyle。这将得出您想要的区别。

https://developer.apple.com/documentation/photos/phasset.playbackstyle

.videoLooping 是弹跳或缩放实时照片。