You've learned a lot about measuring your app's performance in this chapter. You've also learned how to find common issues and how to use Instruments to figure out what's going on behind the scenes for your app.

In your day-to-day development cycle, you won't use Instruments or Xcode's memory debugger. However, familiarizing yourself with these tools can literally save you hours of debugging. It can even help you to discover memory leaks or slow code before you ship your app.

Try to audit and measure several aspects of your app while you're developing it and you will see how performance of certain aspects in your app improve or degrade over time. This will help you to avoid shipping an app that's full of slow code or memory leaks. However, don't go overboard with optimizing until you encounter actual problems in your app. Prematurely optimizing your code often leads to hard to maintain code.

The fixes we applied in this chapter are pretty simple, we had a few small bugs that could be fixed in just a few lines of code. Unfortunately, fixing issues in your app isn't always this easy. Sometimes your code is as fast as it can be, yet it still takes too long and it makes scrolling your tables or collections choppy.

In the next chapter, we'll see how to fix this using asynchronous code and operations.