Capturing 'self' strongly

    _player.completionBlock = ^{
            [self stopPlay];

        };

在ARC中

上面在block里用self是会有提示：
Capturing 'self' strongly in this block is likely to lead to a retain cycle

可以这样改一下

    __weak typeof(self)
weakSelf = self;
        _player.completionBlock = ^{
            [weakSelf stopPlay];
        };