Question

I am using three20 and implement the model like the example of TTRemoteExamples. Now problem is: when I click and open a page, the TTURLRequest sent out, during fetch data from remote, I click to open another page. But the previous network request is still there messed my loaded data. So I want to know the way to cancel previous network request when I switch to another page. Or when I click button to do a new request in the same page.

Thanks~

Answer 1

To cancel a TTURLRequest, keep a reference to it (typically in an instance variable) then send it a “cancel” message. Like so:

[self.myRequest cancel];

If you don’t want the delegate to be notified of the request being cancelled, do:

// I'm assuming self is the delegate here, that may not be true
[[self.myRequest delegates] removeObject:self];
[self.myRequest cancel];

You’ll typically also want to do this in your view controller dealloc method. If a request continues after the viewController has been deallocated, it will try to send delegate messages to it, and you’ll get a bad access crash.

As for the timing of when you cancel it, that’s up to you. If you need it to stop when a user leaves your view controller, then implement UIViewController’s viewWillDisappear: or viewDidDisappear: methods (don’t forget to call super!).