预期错误：SwiftUI 函数中非可选参数类型的三元条件 nil

Question

Code below works fine even if optional type isn't what the .gesture() modifier really wants for its parameter type.

someKindOfView
    .gesture(condition ? DragGesture() : nil)
 

Why is this possible?

Many thanks!!!!

Answer 1

Because the Gesture is generic protocol...

and so the gesture modifier accepts generic type conforming to Gesture

and there is such extension confirming Optional to Gesture

so in case of

.gesture(condition ? DragGesture() : nil)

compiler infers type as .gesture(_ gesture: DragGesture?, ... and all works.