In Objective C, how can avoid crashing of app?

Ans. :

There are multiple aspects to your questions, let me try to answer them:

• NSSetUncaughtExceptionHandler only catches uncaught exceptions which is only a small subset of possible crashes. 
• Exceptions in Objective-C are defined to be fatal and it is not recommended to catch them and even more not recommended to run any non-async safe code, which includes any Objective-C and Swift code. 
• To catch crashes you need to setup signal handlers and then only run async-safe code at the time of the crash, which is only a small subset of C. Especially you may not allocate new memory at crash time at all.

NSSetUncaughtExceptionHandler(&HandleException);

signal(SIGABRT, SignalHandler);

signal(SIGILL, SignalHandler);

signal(SIGSEGV, SignalHandler);

signal(SIGFPE, SignalHandler);

signal(SIGBUS, SignalHandler);

signal(SIGPIPE, SignalHandler);

This will works for most situations.