Is it possible to log a method call on an existing class in Objective-C

Question

I am currently programming a kind of analytics kit for some of my apps. Now I want to log every view which was on screen (eg every viewDidAppear: call UIViewController class). The most important thing is, that I do not want to change the code of my existing classes. So my question is, if there is a possibility to log each UIViewController which appeared on screen.

Thanks in advance.

Answer 1

Without having to change your existing code, you could use a category and method swizzling to do exactly what you want.

See here for more info: http://www.cocoadev.com/index.pl?MethodSwizzling

Answer 2

You could create a BaseViewController and inherit all your view controllers from this base controller. Inside the base controller's viewDidAppear, viewDidDisappear etc.. log what you want to.