SwiftUI - 2 处理范围滑块

Question

有没有办法使用 SwiftUI 创建一个有 2 个句柄的 Slider？

我正在开展一个项目，该项目需要设置一个低点和高点以在其间创建随机值，而滑块似乎完美地满足了这一需求。我目前将它实现为 2 个单独的滑块，但它更愿意让它有 1 个带 2 个手柄的滑块。

我一直在搜索，但在 SwiftUI 中找不到任何示例，但我确实在这里找到了我想要做的网页示例：https://jqueryui.com/slider/#range

这可以通过 SwiftUI 在 iOS 中实现吗？

Answer 1

我为您创建了一个自定义滑块。我希望这足以满足您的需求。如果还有什么我可以做的，请告诉我。

滑块：

import SwiftUI
import Combine

//SliderValue to restrict double range: 0.0 to 1.0
@propertyWrapper
struct SliderValue {
    var value: Double
    
    init(wrappedValue: Double) {
        self.value = wrappedValue
    }
    
    var wrappedValue: Double {
        get { value }
        set { value = min(max(0.0, newValue), 1.0) }
    }
}

class SliderHandle: ObservableObject {
    
    //Slider Size
    let sliderWidth: CGFloat
    let sliderHeight: CGFloat
    
    //Slider Range
    let sliderValueStart: Double
    let sliderValueRange: Double
    
    //Slider Handle
    var diameter: CGFloat = 40
    var startLocation: CGPoint
    
    //Current Value
    @Published var currentPercentage: SliderValue
    
    //Slider Button Location
    @Published var onDrag: Bool
    @Published var currentLocation: CGPoint
        
    init(sliderWidth: CGFloat, sliderHeight: CGFloat, sliderValueStart: Double, sliderValueEnd: Double, startPercentage: SliderValue) {
        self.sliderWidth = sliderWidth
        self.sliderHeight = sliderHeight
        
        self.sliderValueStart = sliderValueStart
        self.sliderValueRange = sliderValueEnd - sliderValueStart
        
        let startLocation = CGPoint(x: (CGFloat(startPercentage.wrappedValue)/1.0)*sliderWidth, y: sliderHeight/2)
        
        self.startLocation = startLocation
        self.currentLocation = startLocation
        self.currentPercentage = startPercentage
        
        self.onDrag = false
    }
    
    lazy var sliderDragGesture: _EndedGesture<_ChangedGesture<DragGesture>>  = DragGesture()
        .onChanged { value in
            self.onDrag = true
            
            let dragLocation = value.location
            
            //Restrict possible drag area
            self.restrictSliderBtnLocation(dragLocation)
            
            //Get current value
            self.currentPercentage.wrappedValue = Double(self.currentLocation.x / self.sliderWidth)
            
        }.onEnded { _ in
            self.onDrag = false
        }
    
    private func restrictSliderBtnLocation(_ dragLocation: CGPoint) {
        //On Slider Width
        if dragLocation.x > CGPoint.zero.x && dragLocation.x < sliderWidth {
            calcSliderBtnLocation(dragLocation)
        }
    }
    
    private func calcSliderBtnLocation(_ dragLocation: CGPoint) {
        if dragLocation.y != sliderHeight/2 {
            currentLocation = CGPoint(x: dragLocation.x, y: sliderHeight/2)
        } else {
            currentLocation = dragLocation
        }
    }
    
    //Current Value
    var currentValue: Double {
        return sliderValueStart + currentPercentage.wrappedValue * sliderValueRange
    }
}

class CustomSlider: ObservableObject {
    
    //Slider Size
    final let width: CGFloat = 300
    final let lineWidth: CGFloat = 8
    
    //Slider value range from valueStart to valueEnd
    final let valueStart: Double
    final let valueEnd: Double
    
    //Slider Handle
    @Published var highHandle: SliderHandle
    @Published var lowHandle: SliderHandle
    
    //Handle start percentage (also for starting point)
    @SliderValue var highHandleStartPercentage = 1.0
    @SliderValue var lowHandleStartPercentage = 0.0

    final var anyCancellableHigh: AnyCancellable?
    final var anyCancellableLow: AnyCancellable?
    
    init(start: Double, end: Double) {
        valueStart = start
        valueEnd = end
        
        highHandle = SliderHandle(sliderWidth: width,
                                  sliderHeight: lineWidth,
                                  sliderValueStart: valueStart,
                                  sliderValueEnd: valueEnd,
                                  startPercentage: _highHandleStartPercentage
                                )
        
        lowHandle = SliderHandle(sliderWidth: width,
                                  sliderHeight: lineWidth,
                                  sliderValueStart: valueStart,
                                  sliderValueEnd: valueEnd,
                                  startPercentage: _lowHandleStartPercentage
                                )
        
        anyCancellableHigh = highHandle.objectWillChange.sink { _ in
            self.objectWillChange.send()
        }
        anyCancellableLow = lowHandle.objectWillChange.sink { _ in
            self.objectWillChange.send()
        }
    }
    
    //Percentages between high and low handle
    var percentagesBetween: String {
        return String(format: "%.2f", highHandle.currentPercentage.wrappedValue - lowHandle.currentPercentage.wrappedValue)
    }
    
    //Value between high and low handle
    var valueBetween: String {
        return String(format: "%.2f", highHandle.currentValue - lowHandle.currentValue)
    }
}

滑块实现：

import SwiftUI

struct ContentView: View {
    @ObservedObject var slider = CustomSlider(start: 10, end: 100)
    
    var body: some View {
        VStack {
            Text("Value: " + slider.valueBetween)
            Text("Percentages: " + slider.percentagesBetween)
            
            Text("High Value: \(slider.highHandle.currentValue)")
            Text("Low Value: \(slider.lowHandle.currentValue)")
            
            //Slider
            SliderView(slider: slider)
        }
    }
}

struct SliderView: View {
    @ObservedObject var slider: CustomSlider
    
    var body: some View {
        RoundedRectangle(cornerRadius: slider.lineWidth)
            .fill(Color.gray.opacity(0.2))
            .frame(width: slider.width, height: slider.lineWidth)
            .overlay(
                ZStack {
                    //Path between both handles
                    SliderPathBetweenView(slider: slider)
                    
                    //Low Handle
                    SliderHandleView(handle: slider.lowHandle)
                        .highPriorityGesture(slider.lowHandle.sliderDragGesture)
                    
                    //High Handle
                    SliderHandleView(handle: slider.highHandle)
                        .highPriorityGesture(slider.highHandle.sliderDragGesture)
                }
            )
    }
}

struct SliderHandleView: View {
    @ObservedObject var handle: SliderHandle
    
    var body: some View {
        Circle()
            .frame(width: handle.diameter, height: handle.diameter)
            .foregroundColor(.white)
            .shadow(color: Color.black.opacity(0.15), radius: 8, x: 0, y: 0)
            .scaleEffect(handle.onDrag ? 1.3 : 1)
            .contentShape(Rectangle())
            .position(x: handle.currentLocation.x, y: handle.currentLocation.y)
    }
}

struct SliderPathBetweenView: View {
    @ObservedObject var slider: CustomSlider
    
    var body: some View {
        Path { path in
            path.move(to: slider.lowHandle.currentLocation)
            path.addLine(to: slider.highHandle.currentLocation)
        }
        .stroke(Color.green, lineWidth: slider.lineWidth)
    }
}