在後臺停止音頻

Question

有一個名爲IHeartRadio的應用程序，它可讓您設置一個睡眠定時器，該定時器將在指定的時間間隔後關閉音頻。

您首先選擇要收聽的電臺，然後選擇一段時間後再停止播放。該應用程序不需要在前臺發生這種情況。

應用程序在背景中時如何停止音頻？

一個理論是用無聲音頻設置UILocalNotification。然後，UILocalNotification將接管設備的音頻，實際上可以消除正在播放的任何音頻。這沒有用。

定時器在背景中不起作用，這在後臺基於時間的行爲方面沒有多大意義。

Answer 1

您可以在您的AppDelegate中使用applicationDidEnterBackground事件來處理應用程序進入後臺並停止使用此方法的音頻。

- (void)applicationDidEnterBackground:(UIApplication *)application 
{ 
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. 
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits. 

    // add your audio stopping code .. 
} 

Answer 2

When the UIBackgroundModes key contains the audio value, the system’s media frameworks automatically prevent the corresponding app from being suspended when it moves to the background. As long as it is playing audio or video content, the app continues to run in the background. However, if the app stops playing the audio or video, the system suspends it.

從iOS App Programming Guide。