This chapter presented playgrounds, an innovative way of running Swift code with graphical representation of values and introspection of running code. Both expressions and timeline were presented as a way of showing the state of the program at any time, as well as graphically inspecting objects using Quick Look. The XCPlayground
framework can also be used to record specific values and allow asynchronous code to be executed.
The next chapter will look at how to create an iOS application with Swift.