ios - swift 3 错误 : Type 'AVLayerVideoGravity' has no member 'resizeAspectFill'

Question

我正在使用 Swift 3 开发一个 iOS 应用程序，我在后台播放视频。我的代码工作完全正常，直到随机出现错误消息:

Type AVLayerVideoGravity aka (NSString) has no member resizeAspectFill

出现。我完全不明白为什么 resizeAspectFill 不再被识别。有什么我想念的吗？我试过清理我的项目，但这并没有解决任何问题。任何帮助将不胜感激 :)下面是代码:

import Foundation
import AVFoundation
import UIKit

class HomeViewController: UIViewController {
// MARK: Properties
var avPlayer: AVPlayer!
var avPlayerLayer: AVPlayerLayer!
var paused: Bool = false

var enterButton: UIButton! = UIButton()

override func viewDidLoad() {
    super.viewDidLoad()
    self.title = "Welcome"

    let theURL = Bundle.main.url(forResource:"hannah", withExtension: "mp4")

    avPlayer = AVPlayer(url: theURL!)
    avPlayerLayer = AVPlayerLayer(player: avPlayer)
    avPlayerLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill

    avPlayer.volume = 0
    avPlayer.actionAtItemEnd = .none

    avPlayerLayer.frame = view.layer.bounds
    view.backgroundColor = .clear
    view.layer.insertSublayer(avPlayerLayer, at: 0)

    NotificationCenter.default.addObserver(self,
                                           selector: #selector(playerItemDidReachEnd(notification:)),
                                           name: NSNotification.Name.AVPlayerItemDidPlayToEndTime,
                                           object: avPlayer.currentItem)

Answer 1

来自documentation of AVPlayerLayer (不幸的是，该链接重定向到 Swift 4 版本。要查看更改，请在右上角启用显示 API 更改)。

The video gravity determines how the video content is scaled or stretched within the player layer’s bounds. The player layer supports the following video gravity values:

• AVLayerVideoGravityResizeAspect

• AVLayerVideoGravityResizeAspectFill

• AVLayerVideoGravityResize

The default value is AVLayerVideoGravityResizeAspect.

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您所指的枚举案例属于 Swift 4