使用 AVPlayer 平移手势

Question

此功能对我的应用程序非常重要，并且非常希望得到一些帮助。基本上，我想在视频播放器中添加一个UIPanGestureRecognizer，以便用户可以通过手势快进/快退视频。

Apple 有一些使用 Swift 3 的示例代码，并且已经创建了整个视频播放器。唯一缺少的是UIPanGestureRecognizer。这是链接：https://developer.apple.com/library/content/samplecode/AVFoundationSimplePlayer-iOS/Introduction/Intro.html#//apple_ref/doc/uid/TP40016103

在viewWillAppear 我添加了这样的手势：

let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture))
view.addGestureRecognizer(panGesture)

这是有些工作的代码。目前正在刷机。

问题是每次我开始平移手势时，视频都会跳到中间，我从那里开始。平移手势不是从视频当前所在的位置快进/快退，而是将视频跳过到中间，然后允许我快进/快退，这不好。

func handlePanGesture(sender: UIPanGestureRecognizer) {
    switch sender.state {
    case .began, .changed:
        let translation = sender.translation(in: self.view)
        var horizontalTranslation = Float(translation.x)

        let durationInSeconds = Float(CMTimeGetSeconds(player.currentItem!.asset.duration))

        // Using 275 as the limit for delta along x
        let translationLimit: Float = 275
        let minTranslation: Float = -1 * translationLimit
        let maxTranslation: Float = translationLimit

        if horizontalTranslation > maxTranslation {
            horizontalTranslation = maxTranslation
        }

        if horizontalTranslation < minTranslation {
            horizontalTranslation = minTranslation
        }

        let timeToSeekTo = normalize(delta: horizontalTranslation , minDelta: minTranslation, maxDelta: maxTranslation, minDuration: 0, maxDuration: durationInSeconds)
        print("horizontal translation \(horizontalTranslation) \n timeToSeekTo: \(timeToSeekTo)")

        let cmTime = CMTimeMakeWithSeconds(Float64(timeToSeekTo), self.player.currentTime().timescale)
        player.seek(to: cmTime)

    default:
        print("default")
    }

}

func normalize(delta: Float, minDelta: Float, maxDelta: Float, minDuration: Float, maxDuration: Float) -> Float {

    let result = ((delta - minDelta) * (maxDuration - minDuration) / (maxDelta - minDelta) + minDuration)
    return result
}

任何帮助都会很棒 - 谢谢！

Answer 1

感谢您的代码。我用过，改了几行，效果很好。

   @objc func handlePanGesture(sender: UIPanGestureRecognizer) {
      switch sender.state {
       case .began, .changed:
        let translation = sender.translation(in: self.view)
        let horizontalTranslation = Float(translation.x)

        let durationInSeconds = Float(CMTimeGetSeconds(player.currentItem!.asset.duration))

        // normalize based on duration and width of the view
        let scale:Float = durationInSeconds / Float(self.view.frame.width) / 4
        // then you need to add the current time of player to avoid it starting from the middle.            
        let seekTime = horizontalTranslation * scale + Float((self.player.currentItem?.currentTime().seconds)!)

        let cmTime = CMTimeMakeWithSeconds(Float64(Float(seekTime)), preferredTimescale: self.player.currentTime().timescale)
        player.seek(to: cmTime)
        print("horizontal translation \(horizontalTranslation) \n timeToSeekTo: \(seekTime)")

    default:
        print("default")
    }

}

Answer 2

我已经用AVPlayer 实现了UIPanGesture，下面是我的工作代码[swift 3]。

func handleDraging(_ gesture:UIPanGestureRecognizer){
        let location = gesture.location(in: self.playerView)
        if gesture.state == .began {
            print("\n\n-->---> Panning.state = .began at Point.x = \(location.x)")
            self.playerLayer.player?.rate = 0
            self.stopTimer()
        }else if gesture.state == .changed {
            let valocity = gesture.velocity(in: self.playerView)
            print("\n\n-->---> Panning.state = .changed at Point.x = \(location.x)")
            let percentage = Double(location.x) / Double(self.playerView.frame.width)
            let currentTime = self.playerLayer.player!.currentTime()
            let currentSeconds = CMTimeGetSeconds(currentTime)
            var newSeconds = currentSeconds + percentage
            if valocity.x < 0 {
                newSeconds = currentSeconds - percentage
            }
            let newTime = CMTime(seconds: newSeconds, preferredTimescale: self.playerLayer.player!.currentTime().timescale)
            self.playerLayer.player?.seek(to: newTime, toleranceBefore: kCMTimeZero, toleranceAfter: kCMTimeZero)
            let total = CGFloat(CMTimeGetSeconds(self.playerLayer.player!.currentItem!.asset.duration))
            let seconds = CGFloat(CMTimeGetSeconds(newTime))
            self.interval = Double(seconds)//here update your CurrentTimelabel.text .....

            let temp = seconds/total
            self.progress = Float(temp)//here update your UIProgressBar.progress .....
            print("\n\t-->Total Progress = \(temp)")
        }else if gesture.state == .ended || gesture.state == .failed || gesture.state == .recognized {
            gesture.setTranslation(CGPoint.zero, in: self.playerView)
            self.startTimer()
            self.playerLayer.player?.playImmediately(atRate: 1)
        }
    }