In this chapter, we saw unit tests in action and how they are set up in Xcode. You learned what TDD is and why it can help build better apps. With the help of TDD, we implemented a feature of a demo app to get used to the workflow. We saw many different possibilities to run tests and how we can find bugs in our tests using LLDB, the debugger integrated into Xcode. Finally, we discussed the advantages and disadvantages of TDD and what should be tested with unit tests.

In the next chapter, we will take a look at an app that we will build together using TDD.