AVVlayerItem.loadedTimeRanges上的KVO可能吗？

Question

苹果文档提到了它,但是如何为AVPlayerItem的loadedTimeRanges属性设置键值观察？该属性是一个不会改变的NSArray,所以你不能只使用它playerItem addObserver:self forKeyPath:@"loadedTimeRanges ...

或者是否有其他方法可以在此更改时收到通知或更新？

Answer 1

实际上,我正在使用KVO for loadedTimeRanges而没有任何麻烦.也许你只是没有设置正确的选项？以下是对Apple AVPlayerDemo中某些代码的一个非常小的修改,它对我来说非常好用.

//somewhere near the top of the file
NSString * const kLoadedTimeRangesKey   = @"loadedTimeRanges";
static void *AudioControllerBufferingObservationContext = &AudioControllerBufferingObservationContext;


- (void)someFunction
{  
    // ...

    //somewhere after somePlayerItem has been initialized
    [somePlayerItem addObserver:self
                       forKeyPath:kLoadedTimeRangesKey
                          options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
                          context:AudioControllerBufferingObservationContext];

    // ...
}

- (void)observeValueForKeyPath:(NSString*) path 
                  ofObject:(id)object 
                    change:(NSDictionary*)change 
                   context:(void*)context
{
    if (context == AudioControllerBufferingObservationContext)
    {
        NSLog(@"Buffering status: %@", [object loadedTimeRanges]);
    }
}