Accessing a selector only once per touch gesture

I've a reload开发者_JS百科 method which handles with highly sensitive core data and I want to implement, that the method can not be executed in parallel.

Is there a simply way to implement something like that?

Update

Maybe it's a different problem.

So I've a pinch-gesture and when a user is doing this gesture I want to execute a method only ONCE!

BUT if I'm simulating it right now in the iOS simulator, the method execution starts when a minimal pinch gesture is recognized and is fired as long as the user holds this pinch gesture.

Is this the default usage?!?!? How can I edit it, that the method is only fired once per pinch gesture independent of how long the user is holding this gesture etc.

Yes there is. Check out the @synchronized directive: http://developer.apple.com/library/mac/#documentation/cocoa/conceptual/ObjectiveC/Chapters/ocThreading.html

andi1984,

Of course, you could require that the method only execute on the main thread. As in this example:

- (void) sensitiveMethod {

    // If necessary, rethrow on the main queue.
    if (!NSThread.isMainThread) {

        [[NSOperationQueue mainQueue] addOperationWithBlock: ^{

            [self sensitiveMethod];
        }];
        return;
    }

    // body of your sensitive method here.

} // sensitiveMethod

Andrew