A certificate of expert status in mobile development according to the Worldskills organization.
Certificate giving the right to conduct mobile development championships by Worldskills standards.
A good book for an introduction to the Swift programming language that I read in preparation for an iOS development course.
A course on iOS development from EPAM. After taking this course I was able to learn how to create mobile iOS applications in Swift. Also after finishing the training program as a final project I developed messenger SmallTalk, which became my first big project aimed at iOS.