I have once implemented a complete feature flag architecture for an iOS app. Such an architecture is important to switch features on or off, even remotely so that no new build is required. This blog post describes how the architecture was implemented.
This blog post illustrates how deep linking into an iOS app works.
An important topic for an iOS app may be to use a consistent theming across the whole UI. This blog post shows a few options how to do app theming.
GraphQL is a query language for APIs that provides a complete description of the data used in an API. More details can be found on https://graphql.org/. I have integrated GraphQL on iOS and want to share that knowledge.
This blog post describes how JSON objects can be stored, serialized and deserialized using CoreData.
The AVFoundation framework offers a pretty good way to scan codes with the device camera, such as qr codes or barcodes. This blog post gives an implementation of doing such code scanning.