播放背景音乐在iPhone [英] playing background audio on iphone

问题描述

我怎么能播放背景声音我的应用程序运行时？

How can I play a background audio while my application is running?

感谢。

推荐答案

好吧。这是对iOS4的＆放大器背景音的溶液; iOS5的（肯定工程最多的iOS 5.0.1），而我只用AVPlayer进行了测试。它应该可能是MPMusicPlayerController工作了。

Okay. This is a solution for background sound on iOS4 & iOS5 (definitely works up to iOS 5.0.1), and I have tested it only with AVPlayer. It should probably work for MPMusicPlayerController too.

必需的框架：

• AVFoundation.framework


• AudioToolbox.framework

• AVFoundation.framework
• AudioToolbox.framework

在你的的Info.plist ，该键 UIBackgroundModes 添加音频。

在 MyAppDelegate.h ：

• 参考＆LT; AVFoundation / AVFoundation.h＆GT; ＆安培; ＆LT; AudioToolbox / AudioToolbox.h＆GT;



• 实施方案 AVAudioSessionDelegate ：

@interface MyAppDelegate : NSObject <UIApplicationDelegate, AVAudioSessionDelegate>

定义一个方法 ensureAudio ：

// Ensures the audio routes are setup correctly
- (BOOL) ensureAudio;

在 MyAppDelegate.m ：

• 实施 ensureAudio 方法：

- (BOOL) ensureAudio
{
    // Registers this class as the delegate of the audio session (to get background sound)
    [[AVAudioSession sharedInstance] setDelegate: self];  

    // Set category
    NSError *categoryError = nil;
    if (![[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&categoryError]) {
        NSLog(@"Audio session category could not be set"); 
        return NO;
    }

    // Activate session
    NSError *activationError = nil;
    if (![[AVAudioSession sharedInstance] setActive: YES error: &activationError]) {
        NSLog(@"Audio session could not be activated");
        return NO;
    }

    // Allow the audio to mix with other apps (necessary for background sound)
    UInt32 doChangeDefaultRoute = 1;
    AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryMixWithOthers, sizeof(doChangeDefaultRoute), &doChangeDefaultRoute);

    return YES;
}

在的application：didFinishLaunchingWithOptions：方法，你指定根视图控制器，运行之前 [自ensureAudio] ：

in the application:didFinishLaunchingWithOptions: method, before you assign the root view controller, run [self ensureAudio]:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Configure audio session
    [self ensureAudio];

    // Add the navigation controller's view to the window and display.
    self.window.rootViewController = self.navigationController;
    [self.window makeKeyAndVisible];

    return YES;
}

实施这样的 AVAudioSessionDelegate 方法：

#pragma mark - AVAudioSessionDelegate

- (void) beginInterruption
{

}

- (void) endInterruption
{
    // Sometimes the audio session will be reset/stopped by an interruption
    [self ensureAudio];
}

- (void) inputIsAvailableChanged:(BOOL)isInputAvailable
{

}

确保您的应用程序将继续在后台运行。您可以使用醇' [UIApplication的sharedApplication] beginBackgroundTaskWithExpirationHandler] 如果你想要的，但我觉得有更好的办法。

ensure that your app continues to run in the background. You can use the ol' [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler] if you want, but I think there are better ways.

发挥实际音频（请注意我用的弧线，这就是为什么没有发布话费）：

play the actual audio (note I'm using ARC, that's why there are no release calls):

NSURL * file = [[NSBundle mainBundle] URLForResource:@"beep" withExtension:@"aif"];    
AVURLAsset * asset = [[AVURLAsset alloc] initWithURL:file options:nil];
AVPlayerItem * item = [[AVPlayerItem alloc] initWithAsset:asset];
__block AVPlayer * player = [[AVPlayer alloc]initWithPlayerItem:item];
__block id finishObserver = [[NSNotificationCenter defaultCenter] addObserverForName:AVPlayerItemDidPlayToEndTimeNotification 
                                                                      object:player.currentItem 
                                                                       queue:[NSOperationQueue mainQueue] 
                                                                  usingBlock:^(NSNotification *note) {
    [[NSNotificationCenter defaultCenter] removeObserver:finishObserver];

    // Reference the 'player' variable so ARC doesn't release it until it's
    // finished playing.
    player = nil;
}];

// Trigger asynchronous load
[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"] completionHandler:^{
    // Start playing the beep (watch out - we're not on the main thread here)!
    [player play];
 }];

和它shooooooooooooould工作！

And it shooooooooooooould work!

这篇关于播放背景音乐在iPhone的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！