I have started writing a series of articles/tutorials to help understands the mid-senior level resources to architect the iOS apps.
There are currently two articles on medium that you can follow
Article # 1: Highly Customizable Network Layer in Swift 5 https://medium.com/@waseem.wk22_8164/highly-customizable-network-layer-in-swift-5-1e5c1e163674
Article # 2: Reusable & Generic Database Layer https://medium.com/@waseem.wk22_8164/reusable-generic-database-layer-in-swift-7950d604883b