My iOS app freezes but no error appears

Question

Does any body know what I need to check if app freezes after some time? I mean, I can see the app in the iPhone screen but no view responds.

I did some google and i found that, i've blocked the main thread somehow.

But my question is how to identify which method causes blocking of main thread? is there any way to identify?

Answer 1

Generally, it is highly recommended to perform on the main thread all animations method and interface manipulation, and to put in background tasks like download data from your server, etc...

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    //here everything you want to perform in background

    dispatch_async(dispatch_get_main_queue(), ^{ 
        //call back to main queue to update user interface
    });
});

Source : http://www.raywenderlich.com/31166/25-ios-app-performance-tips-tricks

Answer 2

Launch your app and wait for it to freeze. Then press the "pause" button in Xcode. The left pane should show you what method is currently running.

Answer 3

Set a break point from where the freeze occurs and find which line cause that.

Chances may be,Loading of large data,disable the controls,overload in main thread,Just find out where that occurs using breakpoints and rectify based on that.

Answer 4

I reached an error similar to this, but it was for different reasons. I had a button that performed a segue to another ViewController that contained a TableView, but it looked like the application froze whenever the segue was performed.

My issue was that I was infinitely calling reloadData() due to a couple of didSet observers in one of my variables. Once I relocated this call elsewhere, the issue was fixed.