当Airplay处于活动状态时如何自定义airplay按钮

Question

我已经试着解决这个问题两天了，我放弃了。我正在尝试实现一个自定义的airplay按钮(我必须是因为背景是白色的，按钮必须是黑色的)。我在interfacebuilder中添加了一个视图，并为它选择了mpVolumeView。然后，我建立了连接并编写了以下代码；

viewDidLoad.. {
    .....

    [_volumeView setShowsVolumeSlider:NO];
    for (UIButton *button in _volumeView.subviews) {
        if ([button isKindOfClass:[UIButton class]]) {
            [button setImage:[UIImage imageNamed:@"airplay_icon.png"] forState:UIControlStateNormal];
            [button addObserver:self forKeyPath:@"alpha" options:NSKeyValueObservingOptionNew context:nil];
            [button addTarget:self action:@selector(switchAirplayButton) forControlEvents:UIControlEventTouchUpInside];
            [button sizeToFit];
        }
    }
    [_volumeView sizeToFit];

}

-(void)switchAirplayButton {

    for (UIButton *button in _volumeView.subviews) {
        if ([button isKindOfClass:[UIButton class]]) {

            NSLog(@"%d", _controlBar.player.airPlayVideoActive);

            if(_controlBar.player.airPlayVideoActive) {
                [button setImage:[UIImage imageNamed:@"airplay_icon_pressed.png"] forState:UIControlStateNormal];
            } else  [button setImage:[UIImage imageNamed:@"airplay_icon.png"] forState:UIControlStateNormal];

            [button sizeToFit];
        }
    }


}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if ([object isKindOfClass:[UIButton class]] && [[change valueForKey:NSKeyValueChangeNewKey] intValue] == 1) {
        [(UIButton *)object setImage:[UIImage imageNamed:@"airplay_icon.png"] forState:UIControlStateNormal];
        [(UIButton *)object sizeToFit];
    }
}

"player“是一个基于AVPLayer的单音播放器。但是，当检查airPlay是否处于活动状态时，它总是返回false。也许只是因为我使用的是声音，而不是视频。

所以我的问题是，我怎么才能把按钮改成...当airplay正在播放流媒体时(就像苹果将其设置为蓝色一样)，我们假设它是橙色的(只是为了与界面的其他部分相匹配)。我试过所有的方法，但就是一点也不起作用。请帮帮我。

Answer 1

编辑：

虽然下面的代码可以在iOS 5和6上运行，但从iOS 6.0开始，有一种官方方法可以做到这一点，这要容易得多。只需查看MPVolumeView的文档，特别是– setRouteButtonImage:forState:。

====的老答案：====

这很难实现，但我为iOS 5.0+找到了一种方法。首先，将以下行添加到您的ViewController：

#import <AudioToolbox/AudioToolbox.h>

在你的viewDidLoad中，你已经做对了大部分事情，这是我的代码：

for (id current in self.volumeView.subviews){
    if([current isKindOfClass:[UIButton class]]) {
        UIButton *airPlayButton = (UIButton*)current;
        self.airPlayButton = airPlayButton;
        [self setAirPlayButtonSelected:[self isAirPlayActive]];
        [airPlayButton addObserver:self forKeyPath:@"alpha" options:NSKeyValueObservingOptionNew context:nil];
    }
}

下面是助手setAirPlayButtonSelected方法，它只是设置图像：

- (void)setAirPlayButtonSelected:(BOOL)selected {
    UIImage* image;
    if (selected) {
        image = [UIImage imageNamed:@"button-airplay-selected"];
    }else {
        image = [UIImage imageNamed:@"button-airplay"];
    }
    [self.airPlayButton setImage:image forState:UIControlStateNormal];
    [self.airPlayButton setImage:image forState:UIControlStateHighlighted];
    [self.airPlayButton setImage:image forState:UIControlStateSelected];
}

为了完整起见，observeValueForKeyPath

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

    if (object == self.airPlayButton && [[change valueForKey:NSKeyValueChangeNewKey] intValue] == 1) {
        [self setAirPlayButtonSelected:[self isAirPlayActive]];
    }
}

现在有趣的部分来了。下面是isAirPlayActive助手方法。它使用AudioSession框架来确定当前播放的audioSource。

- (BOOL)isAirPlayActive{
    CFDictionaryRef currentRouteDescriptionDictionary = nil;
    UInt32 dataSize = sizeof(currentRouteDescriptionDictionary);
    AudioSessionGetProperty(kAudioSessionProperty_AudioRouteDescription, &dataSize, &currentRouteDescriptionDictionary);
    if (currentRouteDescriptionDictionary) {
        CFArrayRef outputs = CFDictionaryGetValue(currentRouteDescriptionDictionary, kAudioSession_AudioRouteKey_Outputs);
        if(CFArrayGetCount(outputs) > 0) {
            CFDictionaryRef currentOutput = CFArrayGetValueAtIndex(outputs, 0);
            CFStringRef outputType = CFDictionaryGetValue(currentOutput, kAudioSession_AudioRouteKey_Type);
            return (CFStringCompare(outputType, kAudioSessionOutputRoute_AirPlay, 0) == kCFCompareEqualTo);
        }
    }

    return NO;
}

因此，所有这些代码都会在应用程序启动时正确地更改AirPlay按钮。那更新呢？我们需要监听AudioSource的变化。将以下代码行添加到viewDidLoad中

    AudioSessionAddPropertyListener (kAudioSessionProperty_AudioRouteChange, audioRouteChangeCallback, (__bridge void*)self);

别忘了在dealloc中注销

- (void)dealloc {
    [self.airPlayButton removeObserver:self forKeyPath:@"alpha"];

    AudioSessionRemovePropertyListenerWithUserData(kAudioSessionProperty_AudioRouteChange, audioRouteChangeCallback, (__bridge void*)self);

}

并将此C函数添加到视图控制器的@implementation之上

void audioRouteChangeCallback (void                   *inUserData,
                                       AudioSessionPropertyID inPropertyID,
                                       UInt32                 inPropertyValueSize,
                                       const void             *inPropertyValue) {

    if (inPropertyID != kAudioSessionProperty_AudioRouteChange) {
        return;
    }

    CFDictionaryRef routeChangeDictionary = inPropertyValue;

    CFDictionaryRef currentRouteDescriptionDictionary = CFDictionaryGetValue(routeChangeDictionary, kAudioSession_AudioRouteChangeKey_CurrentRouteDescription);
    CFArrayRef outputs = CFDictionaryGetValue(currentRouteDescriptionDictionary, kAudioSession_AudioRouteKey_Outputs);
    if(CFArrayGetCount(outputs) > 0) {
        CFDictionaryRef currentOutput = CFArrayGetValueAtIndex(outputs, 0);
        CFStringRef outputType = CFDictionaryGetValue(currentOutput, kAudioSession_AudioRouteKey_Type);

        [(__bridge SettingsViewController*)inUserData setAirPlayButtonSelected:CFStringCompare(outputType, kAudioSessionOutputRoute_AirPlay, 0) == kCFCompareEqualTo];
    }

}

正如您所看到的，它所做的全部工作就是确定AirPlay输出源是否处于活动状态，并相应地调用setAirPlayButtonSelected方法。

请参阅苹果的Audio Session Programming Guide，特别是this section，了解回调的确切工作方式等的详细信息。

Answer 2

看看这个类似的link here.

我不确定这是否有效，但尝试制作一个带有airplay符号的黑色按钮，然后将其放在很难看到的airplay按钮的顶部。您应该将用户交互设置为禁用。试试看，这可能是一个更简单的解决方案。

*不要忘记在属性检查器和身份检查器上禁用用户交互。