UI changes on background thread due to NSUserDefaultsDidChangeNotification

Question

I am debugging an issue that occasionally causes my app to crash with a WebTryThreadLock message in the crash report. It looks like the app is crashing because

Answer 1

You should send a message to the UI thread's dispatch queue and do your UI modifications from there.

Like this:

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

See Apple's Grand Central Dispatch documentation

--- Dave