It's not about "having to" in as much as it is about what you are aiming to accomplish?

SwiftUI, is still young and therefore, with many changes upcoming. It still is missing some features. But it seems to be the future with a constant rise of tutorials and reference material. I am loving it. I am sticking with it, and not looking back.

UIKit is great. It's how you build apps now. Today. So if you are expecting to learn Swift and start coding / publishing within a year, then you might want to start with UIKit.

Keep in mind the shift from UIKit to SwiftUI is very easy. BUT the switch from SwiftUI to UIKit will be painful.

So... are you patient and willing to constantly have to change and maybe relearn things and sometimes try to figure things out alone (SwiftUI)? Or do you want something with Tons of supporting material and answers to all your questions with full integration with the system(UIKit)?