How to delete all NSLog's & comments from my Xcode application?
as a Dev, I can offer these two methods, although I agree with Daniel, that Stack Overflow is a better place to ask this.

Anyway, the first is a simple replace.

Shift-Option-f. Then type NSLog. That will find all the occurances of NSLog in your app.

Then switch find to replace. Then replace "NSLog" with "//NSLog". That will comment out all of them. 

A second - better option takes a bit more work.

First, do the above but instead of replacing the string with "//NSLog", replace it with something like "DLog".

Then, in the prefix.pch file.. Write something like this:

#ifdef DEBUG
#    define DLog(...) NSLog(__VA_ARGS__)
#else
#    define DLog(...) 
#endif
#define ALog(...) NSLog(__VA_ARGS__)


This way, while your app is in debug mode, all the logs will appear, but when you move your app to release mode, the logs are hidden.

Hope this helps.