Handling Thread Safety When Updating UI from a Custom Background Queue in Objective-C
Quick question that's been bugging me - I'm wondering if anyone has experience with I'm working through a tutorial and I'm working with a threading scenario when trying to update my UI from a custom background queue in an Objective-C application... I'm using a dispatch queue for some heavy data processing tasks, and once the data is ready, I need to update a UILabel on the main thread. However, I'm experiencing intermittent crashes with the behavior message: `*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable to set the text of UILabel because it is not on the main thread'`. Here’s a snippet of the code I’m using to manage the background processing and UI update: ```objective-c dispatch_queue_t backgroundQueue = dispatch_queue_create("com.example.myapp.background", DISPATCH_QUEUE_SERIAL); dispatch_async(backgroundQueue, ^{ // Simulate heavy data processing NSString *processedData = [self performHeavyDataProcessing]; dispatch_async(dispatch_get_main_queue(), ^{ self.myLabel.text = processedData; }); }); ``` I've wrapped the UI update code in `dispatch_async(dispatch_get_main_queue(), ^{...});` to ensure it runs on the main thread. However, there are still moments when it crashes. I've also verified that `self.myLabel` is not nil when the UI update is called, which makes this behavior confusing. I've tried using `dispatch_sync` instead of `dispatch_async`, thinking it might help, but it only caused deadlocks and further crashes. Is there a specific way I should be handling the threading to ensure that the UI updates are always performed safely? Any advice or alternative strategies would be greatly appreciated! I'd really appreciate any guidance on this. I'm using Objective-C LTS in this project. This is happening in both development and production on Debian. Any pointers in the right direction? This issue appeared after updating to Objective-C stable. I'd love to hear your thoughts on this. This is my first time working with Objective-C latest. Is this even possible?