iPhone: NSTimer

Have a question... I have Timer

 [NSTimer scheduledTimerWithTimeInterval:120                                                              
target:self                                           
selector:@selector(action1:)                                                      
userInfo:nil                                       开发者_如何学编程                
repeats:YES];

But when I move to another screen of my app I want to change selector...How can I change selector ? I know that I can stop my timer and set a new one, but I don't wont to reset a time remained to fire action...Thanks....

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You can't. NSTimer takes its targeting information in its instantiation methods, and doesn't expose any properties to modify that later.

You're going to have to invalidate this timer and create a new one on the new target.

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It looks like the selector is immutable. I would wrap this functionality into it's only tiny class with a setSelector method. Internally, create the NSTimer with a private selector. Inside that method, call the external selector that's been set using the setSelector method.

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You might call a generic selector that, depending on the page shown, calls other methods:

    [NSTimer scheduledTimerWithTimeInterval:120                                                              
    target:self                                           
    selector:@selector(selectorDispatcher)                                                      
    userInfo:nil                                                       
    repeats:YES];

and than obviously your method selectorDispatcher will look something like:

    - (void) selectorDispatcher{

         if(pageshown1)
            [self callmethod1];
         else
            [self callmethod2];
    }

I think this should work...let me know!