使用AVPlayer自定义播放器，重写网络请求部分，实现边下边播
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(void)viewDidLoad {
[super viewDidLoad];
_VView = [[XPVideoPlayerView alloc]init];
[self.view setBackgroundColor:[UIColor whiteColor]];
_VView = [[XPVideoPlayerView alloc] initWithFrame:CGRectMake(0, CGRectGetHeight([[UIApplication sharedApplication]statusBarFrame])+CGRectGetHeight(self.navigationController.navigationBar.frame), CGRectGetWidth(self.view.frame),CGRectGetWidth(self.view.frame)*9/16)];
_VView.delegate = self;
[_VView setVideoFillMode:AVLayerVideoGravityResizeAspect];
XPVideoPlayer * player = [[XPVideoPlayer alloc]init];
[player enableTimeUpdates];
[player enableAirplay];
[player setURL:[NSURL URLWithString:@"https://dn-xpdu.qbox.me/A%20Shaw%20way%20to%20fly%20Alexander%20technique..Butterfly%20lesson%201.mp4"]];
[player setSupportCache:YES];
[_VView setPlayer:player];
[player play];
[_VView setFrame:[UIScreen mainScreen].bounds];
[self.view addSubview:_VView];
}