New developer

Be more specific.

There are many aspects to app development.

Looking at the topic of software engieering for guidance: take some time to determine and research the platform, technologies and requirements involved in a project.

I recommend reading books and articles on what you want to learn. If its Swift you want to learn, watch Apple development videos and take a look at their included example code.

expand my knowledge in the app development, you have a lot of material in Apple's library (search for Swift in the library): Depending where you start from:

• intro to app development with Swift (beginner)
• Develop in Swift - fundamentals
• Develop in Swift: Explorations - more advanced
• The programming Swift language, for deep knowledge of Swift

If you want to learn SwiftUI, this tutorial is a good start: https://developer.apple.com/tutorials/swiftui