Is the SwiftUI tapGesture super greedy?

Question

Swift 5, iOS 13

This code works if I change the second Gesture to say a LONG Press, but leave them both as tap and it never shows the red box? Am I going mad?

import SwiftUI

struct SwiftUIViewQ: View {
@State var swap: Bool = false
var body: some View {
  VStack {
    if swap {
      SquareView(fillColor: Color.red)
      .onTapGesture {
        self.swap = false
      }
    } else {
      SquareView(fillColor: Color.blue)
      .onTapGesture {
        self.swap = true
      }
    }
  }
}
}

struct SquareView: View {
@State var fillColor: Color
var body: some View {
    Rectangle()
      .fill(fillColor)
      .frame(width: 128, height: 128)
      .onAppear {
        print("fillColor \(self.fillColor)")
      }
}
}

Oddly if I add an onAppear to the first view, it works... if I than add an onAppear to the second it breaks it again..

Works fine with Xcode 12 just by copy/paste – Asperi Jul 01 '20 at 14:16 — Asperi, Jul 01 '20 at 14:16

score 1 · Accepted Answer · answered Jul 01 '20 at 14:21

1

var fillColor doesn't need @State, just remove that and it'll work fine

struct SquareView: View {
    var fillColor: Color
    var body: some View {
        Rectangle()
          .fill(fillColor)
          .frame(width: 128, height: 128)
          .onAppear {
            print("fillColor \(self.fillColor)")
          }
    }
}

answered Jul 01 '20 at 14:21

Ludyem

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Ok, but why does making fillColor a State break it. – user3069232 Jul 01 '20 at 14:51
@user3069232 I think it's because you are not supposed to initialize a State var from another view, you either use an init or Binding for that – Ludyem Jul 02 '20 at 01:52

Is the SwiftUI tapGesture super greedy?

1 Answers1