The string functions of most programming languages can cause performance slowdowns when they are frequently used. With iOS development you will see NSString references and its method calls all over the place. It is well known that Objective-C does have a little overhead when compared to C language that it extends because of the Smalltalk style messaging that goes on behind the scenes. In this post we'll measure the performance of the NSString stringWithFormat: method against C's sprintf function. Additionally, to even the score, following the sprintf function, the C string will be converted to an NSString. Each method will be executed a total of 100,000 times and the time span caluated and charted.