How to use the background thread in Objective-C?

Question

I am trying to run a while loop when I　push the button, but I can not push the button because the while loop blocks the UI.

Is there a background thread where I can run the while loop and also push the UIButton?

Answer 1

Personally, I'd run a HUD activity indicator over the top of the UI and then run your loop in the background.

//Start the HUD here

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

    //Run your loop here

    dispatch_async(dispatch_get_main_queue(), ^(void) {
         //stop your HUD here
         //This is run on the main thread


    });
});

Answer 2

Try this

dispatch_async(dispatch_get_main_queue(), ^{
//  your code
});

Once it dispatches, you will not have full control over the operation. If you want to take the control of the operation. Use

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue addOperationWithBlock:^{

   // Background work
}];