Speed Cross-platform frameworks hit the lowest common denominator. Native SwiftUI uses your iPhone's full hardware—animations are smoother, gestures are faster, responsiveness feels instant. When you pick up your phone to use, you want it now, not waiting for a framework to render.
Design users already know I didn't want users to learn custom UI. Native apps can use Apple's design patterns—the same buttons, gestures, transitions they see in Mail, Notes, Safari. The interface is gone. Zero learning curve.
Hardware-specific features work naturally. Dark mode, dynamic type, accessibility, widgets, orientation control—these integrate seamlessly in native apps because they're built on the same foundation as the OS itself.
If you are a developer for iOS reading this... 1. are you using SwiftUI or something cross-platform... and why? 2. are you trying to have your app with similar feel to Apple apps, or are you creating your custom graphical UI... and why?