Summary
In this chapter, we covered many tools that would boost your productivity. REPL and Playgrounds are perfect for trying out new code and quick code prototyping. Playgrounds can also be used to create interactive documentation and tutorials. Then we covered debugging tools (such as LLDB and REPL) in Xcode, which are very useful for checking the results of operations performed at runtime. The performance of an application can be measured in Instruments or using the console log. To make sure that the performance doesn't decrease, you should use unit testing.
Basically, in this chapter, you learned many tools for discovering slow and problematic code, and in the next chapter, you will learn how to improve and optimize it.
