ios – Form not re-animating in SwiftUI

To get your animation begin once more, you want to reset part worth earlier than begin animation. After WaveView seem, part worth get set to .pi * 2, then whenever you press button, you simply set it to the identical worth, SwiftUI don’t see any change of part so your animation shouldn’t be run, additionally when onChange closure of isAnimating get known as, a brand new withAnimation block get known as subsequently present animation repeatForever get cancel as a result of animation for part and energy are stick collectively in AnimatablePair:

personal func animateWave() {
    part = 0 // <- reset part worth right here
    withAnimation(Animation.linear(length: 2).repeatForever(autoreverses: false)) {
        self.part = .pi * 2
    }
}

You possibly can remark out withAnimation block in onChange(of: isAnimating) to maintain repeatForever animation, however then you’ll not have animation when waveStrength change:

.onChange(of: isAnimating) { _, newValue in
    //withAnimation(.easeInOut(length: 0.5)) {
    waveStrength = newValue ? 50.0 : 0.0
    //}
    if newValue {
        animateWave()
    }
}

One other repair is to seperate part and waveStrength from AnimatablePair:

struct ShapheWave: View, @preconcurrency Animatable {
    var energy: Double
    var frequency: Double
    var part: Double
    
    var animatableData: Double {
        get { part }
        set {
            self.part = newValue
        }
    }
    
    var physique: some View {
        Wave(energy: energy, frequency: frequency, part: part)
            .stroke(.black, lineWidth: 5)
    }
}
struct Wave: Form {
    var energy: Double
    var frequency: Double
    var part: Double = .pi * 2
    var animatableData: Double {
        get { energy }
        set {
            self.energy = newValue
        }
    }
    
    func path(in rect: CGRect) -> Path {
        var path = Path()
        
        let width = Double(rect.width)
        let peak = Double(rect.peak)
        let midHeight = peak / 2
        let wavelength = width / frequency
        
        let firstX = 0.0
        let firstRelativeX = firstX / wavelength
        let firstSine = sin(firstRelativeX + part)
        let firstY = energy * firstSine + midHeight
        path.transfer(to: CGPoint(x: firstX, y: firstY))
        
        for x in stride(from: 0.0, via: width, by: 1) {
            let relativeX = x / wavelength
            let sine = sin(relativeX + part)
            let y = energy * sine + midHeight
            path.addLine(to: CGPoint(x: x, y: y))
        }
        
        return path
    }
}

struct WaveView: View {
    @Binding var isAnimating: Bool
    @State personal var part = 0.0
    @State personal var waveStrength = 50.0
    
    var physique: some View {
        VStack {
            ShapheWave(energy: waveStrength, frequency: 30, part: part)
                .onChange(of: isAnimating) { _, newValue in
                    waveStrength = newValue ? 50.0 : 0.0
                }
                .onAppear {
                    animateWave()
                }
                .animation(.linear(length: 2).repeatForever(autoreverses: false), worth: part)              .animation(.easeInOut(length: 0.5), worth: waveStrength)
        }
    }
    
    personal func animateWave() {
        part = .pi * 2
    }
}