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iOS: The + number values in backtraces (in crash logs)

I'm trying to learn how to understand crash logs better and am doing OK so far. I've noticed one part that wasn't explained in Diagnosing Issues Using Crash Reports and Device Logs. This is the + number value at the end of each part of the backtrace.

Here's an example:

6   UIKit    0x38bf3e7c -[UIViewController window:willAnimate:duration:] + 704

What does the + 704 refer to?

Much thanks

Solution

  • The number stands for bytes offset from the entry point of the method to the instruction which caused the crash.

    Check out this thread describing how to read and understand stack traces. The tutorial by Ray Wenderlich about dealing with app crashes under iOS in general is also a very good source.