Question

I have an app where I want to have an image animation while I am reading some info from a database and building object. I have used UIImageView and set up and array of images, but if I start the animation and then do my DB processing, the animation does not play.

Is there another way to start the animation, or for me to do processing during the animation?

Thanks

Answer 1

It sounds like you’re doing your processing on the main thread, which is preventing your animations from running.

Animations run on the main thread, so to avoid blocking this thread processing should be scheduled on a different thread.

You can achieve this using blocks like so:

dispatch_queue_t queue;
queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

dispatch_async(queue, ^{

    // Your processing to be performed on this thread.
});

Or on earlier iOS versions, like so:

[self performSelectorInBackground:@selector(yourProcessing) withObject:nil];

- (void)yourProcessing {

    // Your processing to be performed on this thread.
}

I highly recommend a read through of the Threading Programming Guide, followed by watching the WWDC sessions covering Blocks and Grand Central Dispatch (WWDC 2009).