Simon Grimm's tutorial provides a comprehensive guide on changing iOS app icons using Capacitor, an open-source tool designed to simplify access to native device functionalities. The process involves setting up an Ionic app with Capacitor, adding the iOS platform, and installing a community plugin developed by John Borges. The tutorial highlights the steps required to integrate alternative icons into the iOS app bundle using Xcode and modify the Info.plist file to reference them. It also details the implementation of a simple user interface within the Ionic app to switch between icons using Capacitor plugin functions such as `getName()`, `isSupported()`, `change()`, and `reset()`. The tutorial underscores the ease of implementing native functionalities with Capacitor, without relying on complex configurations, and encourages developers to explore creating custom plugins if needed. Additionally, Grimm promotes his online Ionic Academy for further learning and development support.