swiftui-pausable-animation

Easily pause and resume SwiftUI animations!

Installation

This component is distributed as a Swift package. Just add this repo's URL to XCode:

https://github.com/globulus/swiftui-pausable-animation

How to use

Add the pausableAnimation modifier to your view. It takes five parameters:

1. binding - the property changed when animating, e.g opacity, offset, rotation angle, etc. It needs to be a @Binding since the modifier will change its value when the animation is paused or resumed.
2. targetValue - this is the final value you're setting the animated property to. E.g, if you're fading something in by changing the opacity from 0 to 1, this value will be 1. The modifier needs to know it in order to be able to resume the animation.
3. remainingDuration - this is a block that tells how for long does the animation last, depending on its current position. E.g, if you're changing opacity from 0 to 1 over 5 seconds, and pause the animation at 2 seconds, the current opacity will be 0.4. This block should be able to take 0.4 and say that 3 seconds more are needed to complete the animation.
4. animation - this is a block that tells which animation to use on resume. Its parameter is the duration of the animation, derived from calling remainingDuration.
5. isPaused - set this binding to true to pause the animation and to false to resume it.

import SwiftUIPausableAnimation

struct PausableAnimationTest: View {
  @State private var angle = 0.0
  @State private var isPaused = false
  
  private let duration: TimeInterval = 6
  private let startAngle = 0.0
  private let endAngle = 360.0
  private var remainingDuration: RemainingDurationProvider<Double> {
    { currentAngle in
      duration * (1 - (currentAngle - startAngle) / (endAngle - startAngle))
    }
  }
  private let animation: AnimationWithDurationProvider = { duration in
    .linear(duration: duration)
  }
  
  var body: some View {
    VStack {
      ZStack {
        Text("I'm slowly rotating!")
          .rotationEffect(.degrees(angle))
          .pausableAnimation(binding: $angle,
                             targetValue: endAngle,
                             remainingDuration: remainingDuration,
                             animation: animation,
                             paused: $isPaused)
      }
      .frame(height: 300)
      Button(isPaused ? "Resume" : "Pause") {
        isPaused = !isPaused
      }
    }
    .onAppear {
      angle = startAngle
      withAnimation(animation(duration)) {
        angle = endAngle
      }
    }
  }
}

Recipe

Check out this recipe for in-depth description of the component and its code. Check out SwiftUIRecipes.com for more SwiftUI recipes!

Changelog

• 1.0.0 - Initial release.