The chart below illustrates the results of 10 runs on an iPad 3 device. In most cases using sprintf that gets converted to an NSString is 2.5x faster than the NSString stringWithFormat: method! Other iOS devices have comparable results in that they retain their 2.5x performance increase, but the total execute time can be slower or faster. In apps or custom controls that make frequent use of NSString stringWithFormat: changing over to the sprintf function would be beneficial for performance.

Note: Testing on the iOS simulator will result in varied performance, this is due to hardware architecture differences.