How to add a KVO to MPMoviePlayer currentPlaybackTime?
问题 How can I add a KVO to the currentPlaybackTime property of a MPMoviePlayer class? 回答1: You cannot add a KVO to currentPlaybackTime since the property is not explicitly declared as KVO compatible. Instead, you could try polling the player regularly and storing the position, with code such as: - (void) BeginPlayerPolling { self.pollPlayerTimer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(PollPlayerTimer_tick:) userInfo:nil repeats:YES]; } - (void) PollPlayerTimer