Unit Testing is a must-have skill especially if you are planning to join a bigger company.
Most of the video tutorials in this playlist come from my video course on Testing Swift Mobile Apps.
The target audience of this video course is a beginner Swift developer with no experience in Unit testing or UI testing. Advanced Unit Testers will not benefit from it much. It starts with Unit Test basics and continues with a very practical set of lessons that demonstrates how to follow a Test-Driven process to implement the User Signup feature in the Model View Presenter mobile app.
If you are a freelance developer you might postpone learning how to unit test iOS app for some time. But if you are planning to join a bigger team, then unit testing is a must-have skill for you to be able to work on important app features.