My team which manages our company's ecommerce website inherited maintaining an iOS app that was being developed by a contracting firm. No one on my team had much experience in iOS. My company is extremely frugal. I bought an intro to iOS course on Udemy for the five of us for about fifty dollars total. It was excellent. Was definitely blown away by the quality and the price. It got us quickly up to speed on xcode, debugging, swift, view creation and publishing to the app store among other things. I am sure there is junk content on udemy, but there is also really good content that is worth more than the price.