如何将 KVO 添加到 MPMoviePlayerController 以便我可以检测控件何时可见

Question

我希望能够使用 MPMoviePlayerController 的标准控件来显示和消失我的自定义控件。最好的方法是什么？

谢谢，

罗布

Answer 1

我相信我找到了解决方案。如果其他人需要此功能，以下是我如何让它工作：

我使用了我找到的代码 此处可在 MPMoviePlayer 视图数组中查找 MPInlineVideoOverlay 子视图。然后我修改如下：

- (void)observeValueForKeyPath:(NSString *)keyPath 
                          ofObject:(id)object 
                            change:(NSDictionary *)change 
                           context:(void *)context {


    float newValue = 0;
    if([change objectForKey:NSKeyValueChangeNewKey] != [NSNull null]) 
    {
        newValue = [[change objectForKey:NSKeyValueChangeNewKey] floatValue];
    }
    NSLog(@"player controls are visible: %@", newValue ? @"YES" : @"NO");
    self.controlsView.alpha = newValue;
}

-(void)recursiveViewTraversal:(UIView*)view counter:(int)counter {
    NSLog(@"Depth %d - %@", counter, view); //For debug
    if([view isKindOfClass:NSClassFromString(@"MPInlineVideoOverlay")]) {
        //Add any additional controls you want to have fade with the standard controls here
        mainControlsView = view;
    } else {
        for(UIView *child in [view subviews]) {
            [self recursiveViewTraversal:child counter:counter+1];
        }
    }
}

-(void)setupAdditionalControls {
    //Call after you have initialized your MPMoviePlayerController (probably viewDidLoad)
    mainControlsView = nil;
    [self recursiveViewTraversal:moviePlayer.view counter:0];

    //check to see if we found it, if we didn't we need to do it again in 0.1 seconds
    if(mainControlsView) {
        [mainControlsView addObserver:self forKeyPath:@"alpha"      options:NSKeyValueObservingOptionNew context:NULL];
    } else {
        [self performSelector:@selector(setupAdditionalControls) withObject:nil afterDelay:0.1];
    }
}`

其中 mainControlsView 是 MPMoviePlayer 的标准 Apple 控件，而 self.controlsView 是我的带有自定义控件的视图。 I 键值 观察标准控件视图上的 alpha 属性，并在其更改时更改我的属性以匹配。

抢