如何在后台触发事件？

Question

I am having a method called -(void)callTheEvent .

I am writing a code to call the method by using Notifications. But the problem is like until and unless the user tap on notifications the method will not fire. So here I am thinking to implement like without tapping the notification it needs to fire a method. Is there any way to implement like this without server?

Answer 1

Try to use NSObject's methods

- (void)performSelectorInBackground:(SEL)aSelector withObject:(id)arg;

or

- (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay;

Answer 2

Unless your application is one of a specific category of applications, then your choices are either to schedule a local notification or a remote notification at the specified time. You cannot execute arbitrary code on a scheduled basis while the application in a background suspended state unless it meets specific criteria.

Example of applications that can run in the background:

• Apps that play audible content to the user while in the background, such as a music player app
• Apps that record audio content while in the background.
• Apps that keep users informed of their location at all times, such as a navigation app
• Apps that support Voice over Internet Protocol (VoIP)
• Apps that need to download and process new content regularly
• Apps that receive regular updates from external accessories

You can refer to the iOS App Programming Guide , skip to the section beginning with the heading "Implementing Long-Running Background Tasks" . The criteria noted above are from that reference.