title: iOS 4 Alarm Clock App with Multitasking Support
body: <p>I'm making an alarm clock app with multitasking support. However, I'm stuck with some limitations of the sdk. </p>
  
  <p>I need to play selected alarm sound whenever the alarm time comes with some properties set by the user. 
  These properties: 
  - Alarm sound can be a music from the user's iPod library, and also some sound files in application bundle. 
  - Alarm sound can be set to play as progressive. </p>
  
  <p>Moreover, alarm sound must be played in background in a loop until the user cancels or wakes the app. </p>
  
  <p>First logical thing that came to my mind was to use local notifications, but with local notifications you can play sound files that are only in app bundle(not iPod music) and that are at most 30 seconds long. Also you are not get notified when the user cancels the notification alert, iOS just stops playing your sound. </p>
  
  <p>Now I'm thinking of using background audio playing option and play silence until the alarm time, and then play the alarm sound while also showing a local notification without sound. But again how will I know if user cancelled the local notification alert and stop playing audio. However according to Apple's documentation iPod music playing(and use of shared resources) is still not allowed for an app that is playing background audio. </p>
  
  <p>I also can't understand how some other apps are doing some of these features. For example, Night Stand HD can play iPod music while in the background, and an app named "Progressive Alarm Clock" can play progressive sound while in the background. </p>
  
  <p>Any ideas and suggestions on these issues? Any of your help will be greatly appreciated</p>