I want to do visionOS games. Which one is better, SwiftUI or UIKit? What are the advantages?
Depending on the type of game you are building, you will likely want to use SceneKit, SpriteKit, or RealityKit. SwiftUI is the future, so my recommendation is to start there. Though there are things it does not support and then you have to bridge over to UIKit in those cases.
For games that take full advantage of Vision Pro in an ImmersiveSpace your best bet is RealityKit and SwiftUI imo.
What are the benefits and tradeoffs to using Unity for visionOS game development when compared to RealityKit and SwiftUI?
Is there some docs about how to port my previous 2d games by spritekit to VisionOS?