Texture | ASVideoNode 导致列表卡顿的优化经

需求是视频自动播放，并且列表预加载。

优化 1：

关闭自动播放：

videoView.shouldAutoplay = false

在 node 处于可见状态的时候播放，不可见时暂停：

override func didEnterVisibleState() {
    super.didEnterVisibleState()
    videoView.play()
    if let currentTime = currentTime {
        videoView.currentItem?.seek(to: currentTime)
    }
}

override func didExitDisplayState() {
    super.didExitDisplayState()
    videoView.pause()
    if let currentTime = videoView.currentItem?.currentTime() {
        self.currentTime = .init(value: currentTime.value, timescale: currentTime.timescale)
    }
}

优化 2：

关于获取视频时长：

通过AVURLAsset的duration获取时长会卡顿，然后就换了一种方案：

func videoNode(_ videoNode: ASVideoNode, didSetCurrentItem currentItem: AVPlayerItem) {
    currentItem.addObserver(self, forKeyPath: "duration", options: .new, context: nil)
}


// MARK: - KVO

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    guard let duration = self.videoView.currentItem?.duration else {
        return
    }
    let value: Int = Int(duration.value)
    let scale: Int = Int(duration.timescale)
    let time = value / scale
    
    let minutes = time / 60
    let seconds = time % 60
    
    let minutesString = String(format: "%.2d", minutes)
    let secondsString = String(format: "%.2d", seconds)
    
    durationLabel.attributedText = NSAttributedString.attributedString(string: "\(minutesString):\(secondsString)", font: .systemFont(ofSize: 12, weight: .medium), color: .white)
}

用了Texture，我才知道什么叫做绝对丝滑。

从此以后别跟我说什么列表卡顿优化，都是渣渣。