Getting a “This application is modifying the autolayout engine from a background thread” error?

It needs to be placed inside a different thread that allows the UI to update as soon as execution of thread function completes:

Modern Swift:

DispatchQueue.main.async {
    // Update UI
}

Older versions of Swift, pre Swift 3.

dispatch_async(dispatch_get_main_queue(){
    // code here
})

Objective-C:

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