1. What data passing means in UIKit
2. Why UIKit needs explicit data passing
3. Forward data passing
4. Backward data passing
5. Delegate pattern (deep dive)
6. Closure / callback pattern (deep dive)
7. NotificationCenter (when and why)
8. ARC and memory considerations
9. Common bugs and failure cases
10. Choosing the correct data passing approach

2. Concepts Explained

1. What Data Passing Means in UIKit

Data passing in UIKit refers to explicitly transferring data between view controllers during navigation events such as:

• pushViewController
• popViewController
• present
• dismiss