Rotate View around an other View SwiftUI

UI Frameworks SwiftUI
Jad-T OP
Created Sep ’21
Replies 3
Boosts 0
Views 1.9k
Participants 3

Hello

I created a custom shape in SwiftUI and I am trying to rotate it around a circle, but it works just on the top part of the circle, can you help me make it rotate exactly around the circle?

(And also can I get the same effect using radians? How?)

Here is the code:

import SwiftUI

struct MyGameView: View {
    
    @State private var degress: Double = 0
    
    let timer = Timer.publish(every: 0.05, on: .main, in: .common).autoconnect()
    
    var body: some View {
        VStack{
            ZStack{
                Circle()
                    .frame(width: 80)
                
                ZStack{
                    Circle()
                        .stroke(lineWidth: 1)
                        .frame(width: 300)
                    
                    BallonShape()
                        .scaledToFit()
                        .scaleEffect(0.2)
                        .foregroundColor(.red)
                        .rotationEffect(.degrees(degress), anchor: .bottom)
                        .offset(x: 0, y: -170)
                }
            }
        }
        .onReceive(timer) { input in
            withAnimation(.easeIn(duration: 0.05).speed(10)){
                 degress += 1
            }
        }
    }
}

struct BallonShape: Shape {
    func path(in rect: CGRect) -> Path {
        Path { path in
            path.move(to: CGPoint(x: rect.midX, y: (rect.maxY + rect.midY) / 2))
            path.addCurve(to: CGPoint(x: rect.midX, y: rect.minY), control1: CGPoint(x: (rect.midX + rect.minX) / 2, y: rect.minY), control2: CGPoint(x: (rect.midX + rect.minX) / 2, y: rect.minY))
            path.addCurve(to: CGPoint(x: rect.midX, y: (rect.maxY + rect.midY) / 2), control1: CGPoint(x: (rect.midX + rect.maxX) / 2, y: rect.minY), control2: CGPoint(x: (rect.midX + rect.maxX) / 2, y: rect.minY))
        }
    }
}

Thank You very much!

Answered by OOPer in 687621022

Please try this:

struct MyGameView: View {
    
    @State private var degress: Double = 0
    
    let timer = Timer.publish(every: 0.05, on: .main, in: .common).autoconnect()
    
    var body: some View {
        VStack{
            ZStack{
                Circle()
                    .frame(width: 80)
                
                ZStack{
                    Circle()
                        .stroke(lineWidth: 1)
                        .frame(width: 300)
                    
                    BallonShape()
                        .scaledToFit()
                        .scaleEffect(0.2)
                        .foregroundColor(.red)
                        .offset(x: 0, y: -170)
                        //Uncomment to clarify what is rotating around what
                        //.background(Color(.displayP3, red: 0.7, green: 0, blue: 0.3, opacity: 0.5))
                        .rotationEffect(.degrees(degress), anchor: .center) //<- Move `rotationEffect` after `offset` and use `.center`
                }
            }
        }
        .onReceive(timer) { input in
            withAnimation(.easeIn(duration: 0.05).speed(10)){
                degress += 1
            }
        }
    }
}

You should better try with various sizes of devices or simulators to check if the code works as expected in all the sizes.

Replies  3
Boosts  0
Views  1.9k
Participants  3
Claude31 OP
Sep ’21

I tested your code and it works perfectly. The orange triangle is not always at the same distance, but it turns all around. Tested with

  • Xcode 13.0ß5
  • iPhone 12 Pro Max - iOS 15.0 simulator.

Here are some screen shots:

So, what is the problem ? Is it the distance to the circle ?

Replacing offset

                        .offset(x: 0, y: -170)

with

                        .offset(x: 0, y: -220)

keeps equal distance. Then you will have to adapt path to stick to the circle.

To get in radians, just replace

.rotationEffect(.degrees: degrees) , …

by

.rotationEffect(.radians(someradValue), …
0
OOPer OP
Sep ’21
Accepted Answer

Please try this:

struct MyGameView: View {
    
    @State private var degress: Double = 0
    
    let timer = Timer.publish(every: 0.05, on: .main, in: .common).autoconnect()
    
    var body: some View {
        VStack{
            ZStack{
                Circle()
                    .frame(width: 80)
                
                ZStack{
                    Circle()
                        .stroke(lineWidth: 1)
                        .frame(width: 300)
                    
                    BallonShape()
                        .scaledToFit()
                        .scaleEffect(0.2)
                        .foregroundColor(.red)
                        .offset(x: 0, y: -170)
                        //Uncomment to clarify what is rotating around what
                        //.background(Color(.displayP3, red: 0.7, green: 0, blue: 0.3, opacity: 0.5))
                        .rotationEffect(.degrees(degress), anchor: .center) //<- Move `rotationEffect` after `offset` and use `.center`
                }
            }
        }
        .onReceive(timer) { input in
            withAnimation(.easeIn(duration: 0.05).speed(10)){
                degress += 1
            }
        }
    }
}

You should better try with various sizes of devices or simulators to check if the code works as expected in all the sizes.

0
Jad-T OP
Sep ’21

It works, Thank You OOPer!

0
Rotate View around an other View SwiftUI
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