String Formatting Tricks/Docs

Question

Was reading the response by Shaggy Frog to this post and was intrigued by the following line of code:

NSLog(@\"%@\", [NSString stringWithFormat:@\"%@:%*s%5.         


        

Answer 1

The documentation of -stringWithFormat leads you to String Format Specifier which in turn sends you to the IEEE printf specification. That's about as much information as you'll ever want.

The only notable exception:

%@

Objective-C object, printed as the string returned by descriptionWithLocale: if available, or description otherwise. Also works with CFTypeRef objects, returning the result of the CFCopyDescription function.

• nil gets converted to (null), that's the reason why NSLog(@"%@", someObject) is safer than NSLog("someObject). The later might crash when someObject is nil:

You might also be interested in the wikipedia page about string formatting.