For my research at school, we are building an iOS application to help the visually impaired navigate through new environments. To do so, we had to go through a few Swift tutorials. Here are some that were provided that I found helpful:

https://docs.swift.org/swift-book/GuidedTour/GuidedTour.html

Start Developing iOS (Swift):

https://developer.apple.com/library/archive/referencelibrary/GettingStarted/DevelopiOSAppsSwift/index.html#//apple_ref/doc/uid/TP40015214-CH2-SW1

This one is a little outdated, but it still serves to introduce the main concepts and functions.

iOS Glossary:

https://developer.apple.com/library/archive/referencelibrary/GettingStarted/DevelopiOSAppsSwift/GlossaryDefinitions.html#//apple_ref/doc/uid/TP40015214-CH12-SW1