ios - ButtonStyle 支持不同的形状

Question

我正在使用自定义 ButtonStyle 创建一个 Button。我希望这个按钮样式支持两种不同的“外观”——圆形或圆角矩形。为此，我为外观情况定义了一个枚举，并将其传递给 ButtonStyle，以便它可以根据需要修改其属性。我遇到了一个问题，即尝试为 clipShape() 提供不同的 Shape。我返回一些 Shape 时出现编译时错误:

Function declares an opaque return type, but the return statements in its body do not have matching underlying types

解决此错误并实现所需按钮外观的好方法是什么？

struct FloatingButton: View {
    enum FloatingButtonStyleType {
        case circle
        case roundedRectangle
    }

    private let image: Image
    private let style: FloatingButtonStyleType
    private let action: () -> ()

    var body: some View {
        Button(action: action) {
            image
        }
        .buttonStyle(FloatingButtonStyle(style: style))
    }

    init(image: Image, style: FloatingButtonStyleType, action: @escaping () -> ()) {
        self.image = image
        self.style = style
        self.action = action
    }
}

struct FloatingButtonStyle: ButtonStyle {
    let style: FloatingButton.FloatingButtonStyleType

    func makeBody(configuration: Self.Configuration) -> some View {
        configuration.label
            .padding(.all, 10)
            .background(Color.black)
            .clipShape(clipShape())
    }

    private func clipShape() -> some Shape { //FIXME: Function declares an opaque return type, but the return statements in its body do not have matching underlying types
        switch style {
        case .circle:
            return Circle()
        case .roundedRectangle:
            return RoundedRectangle(cornerRadius: 5, style: .continuous)
        }
    }
}

Answer 1

这是可能的方法(编译和工作，使用 Xcode 11.2/iOS 13.2 进行测试)

struct FloatingButtonStyle: ButtonStyle {
    let style: FloatingButton.FloatingButtonStyleType

    struct StyleModifier : ViewModifier {
        let style: FloatingButton.FloatingButtonStyleType

        func body(content: Self.Content) -> AnyView {
            switch style {
            case .circle:
                return AnyView(content.clipShape(Circle()))
            case .roundedRectangle:
                return AnyView(content.clipShape(RoundedRectangle(cornerRadius: 5, 
                               style: .continuous)))
            }
        }
    }

    func makeBody(configuration: Self.Configuration) -> some View {
        configuration.label
            .padding(.all, 10)
            .background(Color.black)
            .modifier(StyleModifier(style: style))
    }

}