Swift withAnimation 动画完成监听

dounine2024-08-16 13:16

在ios17中withAnimation有completion方法可以监听动画完成，但是低于ios17没有，需要自定义一个监听器，原理就是通过AnimatableModifier可以监听到值的didSet修改，我们就可以调用回调函数。

代码

swift 复制代码

// 动画完成监听
struct AnimatableCompletionModifier<Value>: AnimatableModifier where Value: VectorArithmetic {
    var animatableData: Value {
        didSet {
            notifyCompletionIfFinished()
        }
    }

    private var targetValue: Value
    private var completion: () -> Void

    init(observedValue: Value, completion: @escaping () -> Void) {
        self.completion = completion
        animatableData = observedValue
        targetValue = observedValue
    }

    private func notifyCompletionIfFinished() {
        guard animatableData == targetValue else { return }
        DispatchQueue.main.async {
            self.completion()
        }
    }

    func body(content: Content) -> some View {
        return content
    }
}

extension View {
    func onAnimationCompleted<Value: VectorArithmetic>(for value: Value, completion: @escaping () -> Void) -> ModifiedContent<Self, AnimatableCompletionModifier<Value>> {
        modifier(AnimatableCompletionModifier(observedValue: value, completion: completion))
    }
}

使用

swift 复制代码

Text("回调")
    .opacity(introTextOpacity)
    .onAnimationCompleted(for: introTextOpacity) {
        print("成功回调了")
    }