performSelectorOnMainThread calling a selector on another viewcontroller

Question

the following code is working just fine:

   NSURL* urlAddressJSonUrl = [NSURL URLWithString:urlString];
        dispatch_async(globalQueue,
                       ^{
                           NSData *imageData = [NSData dataWithContentsOfURL:urlAddressJSonUrl];

                           [self performSelectorOnMainThread:@selector(setImage:)
                                                  withObject:[UIImage imageWithData:imageData] waitUntilDone:NO];
                       });

since I need to call it from different viewControllers I want place it in a general class that has public global help function (+) so I'm looking for a way to pass the selector and the target as parameters for performSelectorOnMainThread to run with

Answer 1

You implied that you have the target. Why don't you just call it with the target?

NSURL* urlAddressJSonUrl = [NSURL URLWithString:urlString];
dispatch_async(globalQueue, ^{
    NSData *imageData = [NSData dataWithContentsOfURL:urlAddressJSonUrl];

   [target performSelectorOnMainThread:@selector(setImage:)
                            withObject:[UIImage imageWithData:imageData]
                         waitUntilDone:NO];
});

Or better

NSURL* urlAddressJSonUrl = [NSURL URLWithString:urlString];
dispatch_async(globalQueue, ^{
    NSData *imageData = [NSData dataWithContentsOfURL:urlAddressJSonUrl];

    dispatch_async(dispatch_get_main_queue(), ^{
        [target setImage:[UIImage imageWithData:imageData]];
    });
});