为 AVPlayer 更新时 UISlider 跳转

Question

我尝试用 UISlider 实现简单的播放器来指示当前音频文件的时间。

在代码中我添加了两个观察者：

    slider.rx.value.subscribe(onNext: { value in
        let totalTime = Float(CMTimeGetSeconds(self.player.currentItem!.duration))
        let seconds = value * totalTime
        let time = CMTime(seconds: Double(seconds), preferredTimescale: CMTimeScale(NSEC_PER_SEC))
        self.player.seek(to: time)
        }).disposed(by: bag)
    let interval = CMTime(seconds: 0.1, preferredTimescale: CMTimeScale(NSEC_PER_SEC))
    player.addPeriodicTimeObserver(forInterval: interval, queue: nil) { [weak self] time in
        self?.updateSlider(with: time)
    }

具有一个私有函数：

private func updateSlider(with time: CMTime) {
    let currentTime = CMTimeGetSeconds(time)
    var totalTime = CMTimeGetSeconds(player.currentItem!.duration)
    if totalTime.isNaN {
        totalTime = 0
    }
    startLabel.text = Int(currentTime).descriptiveDuration
    endLabel.text = Int(totalTime).descriptiveDuration
    slider.value = Float(currentTime / totalTime)
}

当音频播放时，一切正常，滑块几乎更新。当我尝试在播放音频时手动移动滑块时出现问题，然后它跳了。为什么？

更新：

其实我知道为什么。因为我更新了两次：手动和玩家观察者，但如何防止这种行为？我不知道；）请帮忙。

Answer 1

解决此问题的一个简单方法是防止 addPeriodicTimeObserver 在触摸滑块时调用 self?.updateSlider(with: time)。

这可以通过 UISliders isTracking 属性:

来确定

isTracking

A Boolean value indicating whether the control is currently tracking touch events.

While tracking of a touch event is in progress, the control sets the value of this property to true. When tracking ends or is cancelled for any reason, it sets this property to false.

_{Ref: https://developer.apple.com/documentation/uikit/uicontrol/1618210-istracking}

这存在于所有 UIControl 个元素中，您可以这样使用：

player.addPeriodicTimeObserver(forInterval: interval, queue: nil) { [weak self] time in
    //check if slider is being touched/tracked
    guard self?.slider.isTracking == false else { return }

    //if slider is not being touched, then update the slider from here
    self?.updateSlider(with: time)
}

一般示例：

@IBOutlet var slider: UISlider!
//...
func startSlider() {
    slider.value = 0
    slider.maximumValue = 10

    Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [weak self] (timer) in
        print("Slider at: \(self?.slider.value)")
        guard self?.slider.isTracking == false else { return }
        self?.updateSlider(to: self!.slider.value + 0.1)
    }
}

private func updateSlider(to value: Float) {
    slider.value = value
}

_{我确定还有其他（更好）的方法，但我在 RxSwift 方面（还）做得不多。

我希望这已经足够好了。}

为 AVPlayer 更新时 UISlider 跳转

UISlider jumps when updating for AVPlayer

ios

swift

avplayer

uislider

一般示例：