Question

Possible Duplicate:
Intercept method call in Objective-C
How to log all methods used in iOS app

For example, a UIViewController object in iOS receives many messages before its view is shown to a user:

1. viewWillAppear
2. viewWillLayoutSubviews
3. viewDidLayoutSubviews
4. viewDidAppear
5. …

because the framework’s source code is not viewable, we have to rely on books or blogs, or is there a way to print out or monitor all the messages sent to this object by (1) Objective-C, or (2) by any tool?

Answer 1

Rather than my comment, the best approach that I used (and still use) is calling:

(void)instrumentObjcMessageSends(YES);

When I need to start logging all messages and then:

(void)instrumentObjcMessageSends(NO);

Don’t forget to add #import <objc/runtime.h>.
When I don’t need it anymore. The annoying thing is that the log is created under /tmp/msgSends- and this means that you have to open the terminal and use tail to see it in a readable way.

What is printed is something like this:

- CustomTableViewController UIViewController _parentModalViewController
- CustomTableViewController UIViewController isPerformingModalTransition
- CustomTableViewController UIViewController setInAnimatedVCTransition:
- CustomTableViewController UIViewController viewWillMoveToWindow:
- CustomTableViewController UIViewController isPerformingModalTransition
- CustomTableViewController UIViewController parentViewController
- CustomTableViewController UIViewController _popoverController
- CustomTableViewController UIViewController _didSelfOrAncestorBeginAppearanceTransition
- CustomTableViewController UIViewController parentViewController
- CustomTableViewController UIViewController __viewWillDisappear:
- CustomTableViewController UIViewController _setViewAppearState:isAnimating:
- CustomTableViewController UIViewController automaticallyForwardAppearanceAndRotationMethodsToChildViewControllers

Note: It has been a while since I used this approach for the last time and it looks like this approach doesn’t log private methods subclassed. So, if you have a DummyClass with -(void)_dummyMethod as private and then a DummySubClass with a -(void)_dummyMethod implementation, the message will not be logged.

For iOS, this works only on Simulator.