从Xcode 12 beta版(iOS 14)开始，开发者可以使用一个名为ProgressView的新视图，它可以显示确定进度和不确定进度。

它的样式默认为CircularProgressViewStyle，这正是我们正在寻找的。

var body: some View {
    VStack {
        ProgressView()
           // and if you want to be explicit / future-proof...
           // .progressViewStyle(CircularProgressViewStyle())
    }
}

Xcode 11.倍

相当多的视图还没有在SwiftUI中表示，但很容易将它们移植到系统中。 你需要包装UIActivityIndicator并使其UIViewRepresentable。

(关于这方面的更多信息，可以在WWDC 2019的精彩演讲-集成SwiftUI中找到)

struct ActivityIndicator: UIViewRepresentable {

    @Binding var isAnimating: Bool
    let style: UIActivityIndicatorView.Style

    func makeUIView(context: UIViewRepresentableContext<ActivityIndicator>) -> UIActivityIndicatorView {
        return UIActivityIndicatorView(style: style)
    }

    func updateUIView(_ uiView: UIActivityIndicatorView, context: UIViewRepresentableContext<ActivityIndicator>) {
        isAnimating ? uiView.startAnimating() : uiView.stopAnimating()
    }
}

然后你可以使用它如下-这是一个加载叠加的例子。

注意:我更喜欢使用ZStack，而不是overlay(:_)，所以我确切地知道在我的实现中发生了什么。

struct LoadingView<Content>: View where Content: View {

    @Binding var isShowing: Bool
    var content: () -> Content

    var body: some View {
        GeometryReader { geometry in
            ZStack(alignment: .center) {

                self.content()
                    .disabled(self.isShowing)
                    .blur(radius: self.isShowing ? 3 : 0)

                VStack {
                    Text("Loading...")
                    ActivityIndicator(isAnimating: .constant(true), style: .large)
                }
                .frame(width: geometry.size.width / 2,
                       height: geometry.size.height / 5)
                .background(Color.secondary.colorInvert())
                .foregroundColor(Color.primary)
                .cornerRadius(20)
                .opacity(self.isShowing ? 1 : 0)

            }
        }
    }

}

要测试它，你可以使用下面的示例代码:

struct ContentView: View {

    var body: some View {
        LoadingView(isShowing: .constant(true)) {
            NavigationView {
                List(["1", "2", "3", "4", "5"], id: \.self) { row in
                    Text(row)
                }.navigationBarTitle(Text("A List"), displayMode: .large)
            }
        }
    }

}

结果:

如果你想要一个swift-ui风格的解决方案，那么神奇的是:

import Foundation
import SwiftUI

struct ActivityIndicator: View {
    
    @State private var isAnimating: Bool = false
    
    var body: some View {
        GeometryReader { (geometry: GeometryProxy) in
            ForEach(0..<5) { index in
                Group {
                    Circle()
                        .frame(width: geometry.size.width / 5, height: geometry.size.height / 5)
                        .scaleEffect(calcScale(index: index))
                        .offset(y: calcYOffset(geometry))
                }.frame(width: geometry.size.width, height: geometry.size.height)
                    .rotationEffect(!self.isAnimating ? .degrees(0) : .degrees(360))
                    .animation(Animation
                                .timingCurve(0.5, 0.15 + Double(index) / 5, 0.25, 1, duration: 1.5)
                                .repeatForever(autoreverses: false))
            }
        }
        .aspectRatio(1, contentMode: .fit)
        .onAppear {
            self.isAnimating = true
        }
    }
    
    func calcScale(index: Int) -> CGFloat {
        return (!isAnimating ? 1 - CGFloat(Float(index)) / 5 : 0.2 + CGFloat(index) / 5)
    }
    
    func calcYOffset(_ geometry: GeometryProxy) -> CGFloat {
        return geometry.size.width / 10 - geometry.size.height / 2
    }
    
}

简单地使用:

ActivityIndicator()
.frame(width: 50, height: 50)

希望能有所帮助!

使用示例:

ActivityIndicator()
    .frame(width: 200, height: 200)
    .foregroundColor(.orange)

SwiftUI中的活动指标

import SwiftUI

struct Indicator: View {

    @State var animateTrimPath = false
    @State var rotaeInfinity = false

    var body: some View {

        ZStack {
            Color.black
                .edgesIgnoringSafeArea(.all)
            ZStack {
                Path { path in
                    path.addLines([
                        .init(x: 2, y: 1),
                        .init(x: 1, y: 0),
                        .init(x: 0, y: 1),
                        .init(x: 1, y: 2),
                        .init(x: 3, y: 0),
                        .init(x: 4, y: 1),
                        .init(x: 3, y: 2),
                        .init(x: 2, y: 1)
                    ])
                }
                .trim(from: animateTrimPath ? 1/0.99 : 0, to: animateTrimPath ? 1/0.99 : 1)
                .scale(50, anchor: .topLeading)
                .stroke(Color.yellow, lineWidth: 20)
                .offset(x: 110, y: 350)
                .animation(Animation.easeInOut(duration: 1.5).repeatForever(autoreverses: true))
                .onAppear() {
                    self.animateTrimPath.toggle()
                }
            }
            .rotationEffect(.degrees(rotaeInfinity ? 0 : -360))
            .scaleEffect(0.3, anchor: .center)
            .animation(Animation.easeInOut(duration: 1.5)
            .repeatForever(autoreverses: false))
            .onAppear(){
                self.rotaeInfinity.toggle()
            }
        }
    }
}

struct Indicator_Previews: PreviewProvider {
    static var previews: some View {
        Indicator()
    }
}

除了Mojatba Hosseini的回答，

我做了一些更新，这样就可以把它放在一个快速包中:

活动指标:

import Foundation
import SwiftUI
import UIKit

public struct ActivityIndicator: UIViewRepresentable {

  public typealias UIView = UIActivityIndicatorView
  public var isAnimating: Bool = true
  public var configuration = { (indicator: UIView) in }

 public init(isAnimating: Bool, configuration: ((UIView) -> Void)? = nil) {
    self.isAnimating = isAnimating
    if let configuration = configuration {
        self.configuration = configuration
    }
 }

 public func makeUIView(context: UIViewRepresentableContext<Self>) -> UIView {
    UIView()
 }

 public func updateUIView(_ uiView: UIView, context: 
    UIViewRepresentableContext<Self>) {
     isAnimating ? uiView.startAnimating() : uiView.stopAnimating()
     configuration(uiView)
}}

扩展:

public extension View where Self == ActivityIndicator {
func configure(_ configuration: @escaping (Self.UIView) -> Void) -> Self {
    Self.init(isAnimating: self.isAnimating, configuration: configuration)
 }
}

// Activity View

struct ActivityIndicator: UIViewRepresentable {

    let style: UIActivityIndicatorView.Style
    @Binding var animate: Bool

    private let spinner: UIActivityIndicatorView = {
        $0.hidesWhenStopped = true
        return $0
    }(UIActivityIndicatorView(style: .medium))

    func makeUIView(context: UIViewRepresentableContext<ActivityIndicator>) -> UIActivityIndicatorView {
        spinner.style = style
        return spinner
    }

    func updateUIView(_ uiView: UIActivityIndicatorView, context: UIViewRepresentableContext<ActivityIndicator>) {
        animate ? uiView.startAnimating() : uiView.stopAnimating()
    }

    func configure(_ indicator: (UIActivityIndicatorView) -> Void) -> some View {
        indicator(spinner)
        return self
    }   
}

// Usage
struct ContentView: View {

    @State var animate = false

    var body: some View {
            ActivityIndicator(style: .large, animate: $animate)
                .configure {
                    $0.color = .red
            }
            .background(Color.blue)
    }
}

我使用SwiftUI实现了经典的UIKit指示器。 点击这里查看活动指示器的运行情况

struct ActivityIndicator: View {
  @State private var currentIndex: Int = 0

  func incrementIndex() {
    currentIndex += 1
    DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(50), execute: {
      self.incrementIndex()
    })
  }

  var body: some View {
    GeometryReader { (geometry: GeometryProxy) in
      ForEach(0..<12) { index in
        Group {
          Rectangle()
            .cornerRadius(geometry.size.width / 5)
            .frame(width: geometry.size.width / 8, height: geometry.size.height / 3)
            .offset(y: geometry.size.width / 2.25)
            .rotationEffect(.degrees(Double(-360 * index / 12)))
            .opacity(self.setOpacity(for: index))
        }.frame(width: geometry.size.width, height: geometry.size.height)
      }
    }
    .aspectRatio(1, contentMode: .fit)
    .onAppear {
      self.incrementIndex()
    }
  }

  func setOpacity(for index: Int) -> Double {
    let opacityOffset = Double((index + currentIndex - 1) % 11 ) / 12 * 0.9
    return 0.1 + opacityOffset
  }
}

struct ActivityIndicator_Previews: PreviewProvider {
  static var previews: some View {
    ActivityIndicator()
      .frame(width: 50, height: 50)
      .foregroundColor(.blue)
  }
}

试试这个:

import SwiftUI

struct LoadingPlaceholder: View {
    var text = "Loading..."
    init(text:String ) {
        self.text = text
    }
    var body: some View {
        VStack(content: {
            ProgressView(self.text)
        })
    }
}

更多关于SwiftUI ProgressView的信息

自定义指标

虽然苹果现在支持原生活动指示器从SwiftUI 2.0，你可以简单地实现自己的动画。这些都是SwiftUI 1.0所支持的。此外，它还在小部件方面发挥作用。

Arcs

struct Arcs: View {
    @Binding var isAnimating: Bool
    let count: UInt
    let width: CGFloat
    let spacing: CGFloat

    var body: some View {
        GeometryReader { geometry in
            ForEach(0..<Int(count)) { index in
                item(forIndex: index, in: geometry.size)
                    .rotationEffect(isAnimating ? .degrees(360) : .degrees(0))
                    .animation(
                        Animation.default
                            .speed(Double.random(in: 0.2...0.5))
                            .repeatCount(isAnimating ? .max : 1, autoreverses: false)
                    )
            }
        }
        .aspectRatio(contentMode: .fit)
    }

    private func item(forIndex index: Int, in geometrySize: CGSize) -> some View {
        Group { () -> Path in
            var p = Path()
            p.addArc(center: CGPoint(x: geometrySize.width/2, y: geometrySize.height/2),
                     radius: geometrySize.width/2 - width/2 - CGFloat(index) * (width + spacing),
                     startAngle: .degrees(0),
                     endAngle: .degrees(Double(Int.random(in: 120...300))),
                     clockwise: true)
            return p.strokedPath(.init(lineWidth: width))
        }
        .frame(width: geometrySize.width, height: geometrySize.height)
    }
}

不同变奏的演示

Bars

struct Bars: View {
    @Binding var isAnimating: Bool
    let count: UInt
    let spacing: CGFloat
    let cornerRadius: CGFloat
    let scaleRange: ClosedRange<Double>
    let opacityRange: ClosedRange<Double>

    var body: some View {
        GeometryReader { geometry in
            ForEach(0..<Int(count)) { index in
                item(forIndex: index, in: geometry.size)
            }
        }
        .aspectRatio(contentMode: .fit)
    }

    private var scale: CGFloat { CGFloat(isAnimating ? scaleRange.lowerBound : scaleRange.upperBound) }
    private var opacity: Double { isAnimating ? opacityRange.lowerBound : opacityRange.upperBound }

    private func size(count: UInt, geometry: CGSize) -> CGFloat {
        (geometry.width/CGFloat(count)) - (spacing-2)
    }

    private func item(forIndex index: Int, in geometrySize: CGSize) -> some View {
        RoundedRectangle(cornerRadius: cornerRadius,  style: .continuous)
            .frame(width: size(count: count, geometry: geometrySize), height: geometrySize.height)
            .scaleEffect(x: 1, y: scale, anchor: .center)
            .opacity(opacity)
            .animation(
                Animation
                    .default
                    .repeatCount(isAnimating ? .max : 1, autoreverses: true)
                    .delay(Double(index) / Double(count) / 2)
            )
            .offset(x: CGFloat(index) * (size(count: count, geometry: geometrySize) + spacing))
    }
}

不同变奏的演示

眼罩

struct Blinking: View {
    @Binding var isAnimating: Bool
    let count: UInt
    let size: CGFloat

    var body: some View {
        GeometryReader { geometry in
            ForEach(0..<Int(count)) { index in
                item(forIndex: index, in: geometry.size)
                    .frame(width: geometry.size.width, height: geometry.size.height)

            }
        }
        .aspectRatio(contentMode: .fit)
    }

    private func item(forIndex index: Int, in geometrySize: CGSize) -> some View {
        let angle = 2 * CGFloat.pi / CGFloat(count) * CGFloat(index)
        let x = (geometrySize.width/2 - size/2) * cos(angle)
        let y = (geometrySize.height/2 - size/2) * sin(angle)
        return Circle()
            .frame(width: size, height: size)
            .scaleEffect(isAnimating ? 0.5 : 1)
            .opacity(isAnimating ? 0.25 : 1)
            .animation(
                Animation
                    .default
                    .repeatCount(isAnimating ? .max : 1, autoreverses: true)
                    .delay(Double(index) / Double(count) / 2)
            )
            .offset(x: x, y: y)
    }
}

不同变奏的演示

为了防止代码墙，您可以在git托管的这个repo中找到更优雅的指示器。

注意，所有这些动画都有一个必须切换才能运行的Binding。

struct ContentView: View {
    
    @State private var isCircleRotating = true
    @State private var animateStart = false
    @State private var animateEnd = true
    
    var body: some View {
        
        ZStack {
            Circle()
                .stroke(lineWidth: 10)
                .fill(Color.init(red: 0.96, green: 0.96, blue: 0.96))
                .frame(width: 150, height: 150)
            
            Circle()
                .trim(from: animateStart ? 1/3 : 1/9, to: animateEnd ? 2/5 : 1)
                .stroke(lineWidth: 10)
                .rotationEffect(.degrees(isCircleRotating ? 360 : 0))
                .frame(width: 150, height: 150)
                .foregroundColor(Color.blue)
                .onAppear() {
                    withAnimation(Animation
                                    .linear(duration: 1)
                                    .repeatForever(autoreverses: false)) {
                        self.isCircleRotating.toggle()
                    }
                    withAnimation(Animation
                                    .linear(duration: 1)
                                    .delay(0.5)
                                    .repeatForever(autoreverses: true)) {
                        self.animateStart.toggle()
                    }
                    withAnimation(Animation
                                    .linear(duration: 1)
                                    .delay(1)
                                    .repeatForever(autoreverses: true)) {
                        self.animateEnd.toggle()
                    }
                }
        }
    }
}

在SwiftUI 2.0中，我用ProgressView制作了这个简单易用的自定义视图

这是它的样子:

代码:

import SwiftUI

struct ActivityIndicatorView: View {
    @Binding var isPresented:Bool
    var body: some View {
        if isPresented{
            ZStack{
                RoundedRectangle(cornerRadius: 15).fill(CustomColor.gray.opacity(0.1))
                ProgressView {
                    Text("Loading...")
                        .font(.title2)
                }
            }.frame(width: 120, height: 120, alignment: .center)
            .background(RoundedRectangle(cornerRadius: 25).stroke(CustomColor.gray,lineWidth: 2))
        }
    }
}

我的2美分的漂亮和更简单的代码的batuhankrbb，显示使用定时器中的ispresents…或者其他东西…(我将使用它在url回调..)

//
//  ContentView.swift
//
//  Created by ing.conti on 27/01/21.


import SwiftUI

struct ActivityIndicatorView: View {
    @Binding var isPresented:Bool
    var body: some View {
        if isPresented{
            ZStack{
                RoundedRectangle(cornerRadius: 15).fill(Color.gray.opacity(0.1))
                ProgressView {
                    Text("Loading...")
                        .font(.title2)
                }
            }.frame(width: 120, height: 120, alignment: .center)
            .background(RoundedRectangle(cornerRadius: 25).stroke(Color.gray,lineWidth: 2))
        }
    }
}



struct ContentView: View {
    @State var isPresented = false
    @State var counter = 0
    var body: some View {
        
        VStack{
            Text("Hello, world! \(counter)")
                .padding()
            
            ActivityIndicatorView(isPresented: $isPresented)
        }.onAppear(perform: {
            _ = startRefreshing()
        })
    }
    
    
    
    func startRefreshing()->Timer{
        
        let timer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { timer in
            
            counter+=1
            print(counter)
            if counter>2{
                isPresented = true
            }
            
            if counter>4{
                isPresented = false
                timer.invalidate()
            }
        }
        return timer
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

在SwiftUI中，我发现一个方便的方法是两步方法:

Create a ViewModifier that will embed your view into ZStack and add progress indicator on top. Could be something like this: struct LoadingIndicator: ViewModifier { let width = UIScreen.main.bounds.width * 0.3 let height = UIScreen.main.bounds.width * 0.3 func body(content: Content) -> some View { return ZStack { content .disabled(true) .blur(radius: 2) //gray background VStack{} .frame(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height) .background(Color.gray.opacity(0.2)) .cornerRadius(20) .edgesIgnoringSafeArea(.all) //progress indicator ProgressView() .frame(width: width, height: height) .background(Color.white) .cornerRadius(20) .opacity(1) .shadow(color: Color.gray.opacity(0.5), radius: 4.0, x: 1.0, y: 2.0) } } Create view extension that will make conditional modifier application available to any view: extension View { /// Applies the given transform if the given condition evaluates to `true`. /// - Parameters: /// - condition: The condition to evaluate. /// - transform: The transform to apply to the source `View`. /// - Returns: Either the original `View` or the modified `View` if the condition is `true`. @ViewBuilder func `if`<Content: View>(_ condition: Bool, transform: (Self) -> Content) -> some View { if condition { transform(self) } else { self } } } Usage is very intuitive. Suppose that myView() returns whatever your view is. You just conditionally apply the modifier using .if view extension from step 2: var body: some View { myView() .if(myViewModel.isLoading){ view in view.modifier(LoadingIndicator()) } }

如果是myViewModel。isLoading为false，没有修饰符将被应用，因此加载指示器将不显示。

当然，您可以使用任何类型的进度指示器—默认的或您自己的自定义的。

我已经使用AppKit和SwiftUI修改了Matteo Pacini的macOS答案。这允许你在SwiftUI中使用NSProgressIndicator，同时保留macOS 10.15的功能。

import AppKit
import SwiftUI

struct ActivityIndicator: NSViewRepresentable {
    
    @Binding var isAnimating: Bool
    let style: NSProgressIndicator.Style

    func makeNSView(context: NSViewRepresentableContext<ActivityIndicator>) -> NSProgressIndicator {
        let progressIndicator = NSProgressIndicator()
        progressIndicator.style = self.style
        return progressIndicator
    }

    func updateNSView(_ nsView: NSProgressIndicator, context: NSViewRepresentableContext<ActivityIndicator>) {
        isAnimating ? nsView.startAnimation(nil) : nsView.stopAnimation(nil)
    }
    
}

用法如下:

ActivityIndicator(isAnimating: .constant(true), style: .spinning)

基本活动指标结果: