Suspend the application

Question

How can I suspend my application or send a suspend message to my application?

I want to simulate pressing the home button.

Answer 1

There is a private instance method for UIApplication:

The following code would work, (tested in an iPhone 3GS):

UIApplication *app = [UIApplication sharedApplication]; [app performSelector:@selector(suspend)]; 

Answer 2

Quitting your application or sending it to the background programmatically is a violation of the iOS Human Interface Guidelines, which usually doesn't bode well for getting through the review process:

Don’t Quit Programmatically

Never quit an iOS application programmatically because people tend to interpret this as a crash. However, if external circumstances prevent your application from functioning as intended, you need to tell your users about the situation and explain what they can do about it. Depending on how severe the application malfunction is, you have two choices.

Display an attractive screen that describes the problem and suggests a correction. A screen provides feedback that reassures users that there’s nothing wrong with your application. It puts users in control, letting them decide whether they want to take corrective action and continue using your application or press the Home button and open a different application

If only some of your application's features are not working, display either a screen or an alert when people activate the feature. Display the alert only when people try to access the feature that isn’t functioning.

The philosophical reason for this is explained earlier in that document:

People, not applications, should initiate and control actions. Although an application can suggest a course of action or warn about dangerous consequences, it’s usually a mistake for the app to take decision-making away from the user. The best apps find the correct balance between giving people the capabilities they need while helping them avoid dangerous outcomes.

Users feel more in control of an app when behaviors and controls are familiar and predictable. And, when actions are simple and straightforward, users can easily understand and remember them.

People expect to have ample opportunity to cancel an operation before it begins, and they expect to get a chance to confirm their intention to perform a potentially destructive action. Finally, people expect to be able to gracefully stop an operation that’s underway.

There should be no reason that you need to force your application into the background during its operation. It should remain fully functional when displayed onscreen and it should be up to the user when they want to switch away from your application.