iOS 10中的AVPlayerItemFailedToPlayToEndTime在哪里？

// 监听AVPlayerItem的status属性
playerItem.addObserver(self, forKeyPath: "status", options: [.new, .old], context: nil)

// 观察者回调方法
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "status" {
        if let playerItem = object as? AVPlayerItem {
            if playerItem.status == .failed {
                // 处理AVPlayerItemFailedToPlayToEndTime事件
                // ...
            }
        }
    }
}