SwiftUI multiple animations for same element

Question

I'm new to SwiftUI, but I have a good knowledge about Storyboard.

At the beginning I want to start with some animations, but I have a problem with one of them:

I want an image to become the size 50x50 from 0x0 at the beginning.
AFTER it is 50x50 it should repeat an animations that makes the size 50x50 -> 40x40 -> 50x50 -> ... forever

I know @State variables, the .onAppear event, repeating animations with the autoreverse bool, but I don't know how to use them to become the best resolution.

I hope that someone can help me.

@State var element_appeared : Bool = false

Image(systemName: "paperplane.fill")
  .resizable()
  .frame(width: element_appeared ? 50 : 0, height: element_appeared ? 50 : 0)
  .onAppear() {
    element_appeared.toggle()
}
  .animation(.easeInOut)

This is how the animation at the beginning works. I think that I have to work on the element_appeared variable, but I really don't know how..

You need to delay second change. Next should be helpful stackoverflow.com/a/65299904/12299030. — Asperi
– Asperi, Commented Dec 23, 2020 at 9:34
Okay, First I want to thank you for your answer, but I'm to new in SwiftUI to understand the code in the other post :( How can I delay the second animation and how can I ignore the first one, after it made it's job? ^^ — HeroCoder
– HeroCoder, Commented Dec 23, 2020 at 12:59

pawello2222 · Accepted Answer · 2020-12-23 17:25:23Z

4

You can create an enum as you animation has more than two states. Then use DispatchQueue to delay the second animation.

Here is a demo:

enum AnimationState {
    case notAppeared, appeared, animating
}

struct ContentView: View {
    @State private var animationState: AnimationState = .notAppeared
    private let delay: TimeInterval = 1

    var body: some View {
        Image(systemName: "paperplane.fill")
            .resizable()
            .frame(width: imageSize, height: imageSize)
            .onAppear {
                withAnimation(.easeInOut(duration: delay)) {
                    animationState = .appeared
                }
                DispatchQueue.main.asyncAfter(deadline: .now() + delay) {
                    withAnimation(Animation.easeInOut.repeatForever()) {
                        animationState = .animating
                    }
                }
            }
    }

    private var imageSize: CGFloat {
        switch animationState {
        case .notAppeared: return 0
        case .appeared: return 50
        case .animating: return 40
        }
    }
}

answered Dec 23, 2020 at 17:25

pawello2222

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1 Comment

Womble Dec 13, 2024 at 5:58

You can add a .delay() to the second animation, meaning that you don't have to use the DispatchQueue. Cheers.

nicksarno · Accepted Answer · 2020-12-23 17:30:33Z

1

Here's an example. I used a 2nd @State to manage the different animations.

@State var showIcon : Bool = false
@State var animateForever: Bool = false

var body: some View {
    Image(systemName: "paperplane.fill")
        .resizable()
        .frame(width: showIcon ? 50 : 0, height: showIcon ? 50 : 0)
        //.opacity(showIcon ? 1.0 : 0.0)
        .scaleEffect(animateForever ? 0.8 : 1.0) // 0.8 == 40/50
        .onAppear() {
            withAnimation(Animation.easeInOut(duration: 1.0)) {
                showIcon.toggle()
            }
            
            DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
                withAnimation(Animation.easeInOut(duration: 1.0).repeatForever()) {
                    animateForever.toggle()
                }
            }
        }
}

answered Dec 23, 2020 at 17:30

nicksarno

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1 Comment

Womble Dec 13, 2024 at 5:57

You could also leave out the whole DispatchQueue, and just add a .delay(1) to the second animation. Cheers.

Womble · Accepted Answer · 2024-12-13 06:06:12Z

Based on @nicksarno's answer, replacing use of DispatchQueue, with a .delay() on the second animation:

struct AnimatingPlaneView: View {

    @State private var showIcon = false
    @State private var animateForever = false

    private var sideSize: Double { showIcon ? 50 : 0 }
    
    var body: some View {
        Image(systemName: "paperplane.fill")
            .resizable()
            .frame(width: sideSize, height: sideSize)
            .opacity(showIcon ? 1 : 0)
            .scaleEffect(animateForever ? 0.8 : 1)
            .onAppear {
                withAnimation(.easeInOut(duration: 1)) {
                    showIcon.toggle()
                }
                withAnimation(.easeInOut(duration: 1).repeatForever().delay(1)) {
                    animateForever.toggle()
                }
            }
    }
}

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