Question: Does any body know what I have to check if my app freezes? I mean, I can see the app in the iPad screen but no buttons respond. I have tried debugging the code when I click on the button, but I haven't seen anything yet. I was reading about the Instruments tools; specifically how do I use them?

Can anybody help me? I just need an explanation about how use the tools.

Answer: 
Top answer is correct. You can debug this with "Pause" option. Most common way to block main thread is to call `dispatch_sync` on the same thread you dispatching. Sometimes you call same code from `dispatch_once`.
The same Issue Happened to me with ios 13.4 and then I tried the above solution but it doesn't solve it. so I had one element with break constraint on the storyboard. So after resolving the constraint it solve the problem.