Profile with Instruments in iOS

Xcode includes a performance tuning application named Instruments that you can use to profile your application using all sorts of different metrics. They have tools to inspect CPU usage, memory usage, leaks, file/network activity, and energy usage, just to name a few. It’s really easy to start profiling your app from Xcode, but it’s sometimes not as easy to understand what you see when it’s profiling, which deters some developers from being able to use this tool to its fullest potential.

Time Profiler

The first instrument you’ll look at is the Time Profiler. At measured intervals, Instruments will halt the execution of the program and take a stack trace on each running thread. Think of it as pressing the pause button in Xcode’s debugger.Here’s a sneak preview of the Time Profiler :-

This screen displays the Call Tree. The Call Tree shows the amount of time spent executing in various methods within an app. Each row is a different method that the program’s execution path has followed. The time spent in each method can be determined from the number of times the profiler is stopped in each method. For instance, if 100 samples are done at 1 millisecond intervals, and a particular method is found to be at the top of the stack in 10 samples, then you can deduce that approximately 10% of the total execution time — 10 milliseconds — was spent in…