SwiftUI如何给按钮和.sheet添加if else判断实现随机按钮跳转不同视图

问题原因 #

现有代码仅通过单一Bool类型状态控制弹窗，且弹窗内容硬编码固定为ArmExerciseView，和随机生成的训练部位没有关联，所以无论点击什么内容的按钮都只会弹出手臂训练视图；同时原workoutGen()方法每次调用都会重新生成随机值，存在按钮显示内容和点击后判断的部位不一致的隐患。

最简修复代码 #

struct ContentView: View {
    // 控制弹窗是否弹出
    @State private var showWorkoutView: Bool = false
    // 存储启动时生成的当日固定训练部位
    @State private var todayWorkout: String = ""
    let workouts = ["Arms", "Legs", "Back", "Core"]

    var body: some View {
        VStack {
            VStack {
                Text("Random workout for the day:")
                    .bold()
                    .font(.title)
            }
            Button(todayWorkout) {
                showWorkoutView = true
            }
            .font(.title2)
            .sheet(isPresented: $showWorkoutView, content: {
                // 通过switch分支匹配训练部位，返回对应视图
                switch todayWorkout {
                case "Arms":
                    ArmExerciseView()
                case "Legs":
                    LegExerciseView()
                case "Back":
                    BackExerciseView()
                case "Core":
                    CoreExerciseView()
                default:
                    EmptyView()
                }
            })
        }
        .onAppear {
            // 启动时仅生成一次随机训练部位，避免重复随机导致数据不一致
            todayWorkout = workouts.randomElement() ?? "Arms"
        }
    }
}

注意：代码中的LegExerciseView、BackExerciseView、CoreExerciseView请替换为你自己实现的对应部位的训练视图。

可选优化方案 #

如果需要更规范的状态管理，可使用sheet(item:)构造器实现，无需单独维护弹窗控制Bool变量：

struct ContentView: View {
    // 存储当前要展示的训练部位，nil表示不弹窗
    @State private var selectedWorkout: String?
    @State private var todayWorkout: String = ""
    let workouts = ["Arms", "Legs", "Back", "Core"]

    var body: some View {
        VStack {
            VStack {
                Text("Random workout for the day:")
                    .bold()
                    .font(.title)
            }
            Button(todayWorkout) {
                selectedWorkout = todayWorkout
            }
            .font(.title2)
            .sheet(item: $selectedWorkout, content: { workout in
                switch workout {
                case "Arms": ArmExerciseView()
                case "Legs": LegExerciseView()
                case "Back": BackExerciseView()
                case "Core": CoreExerciseView()
                default: EmptyView()
                }
            })
        }
        .onAppear {
            todayWorkout = workouts.randomElement() ?? "Arms"
        }
    }
}

// 扩展String遵守Identifiable协议，满足sheet(item:)的参数要求
extension String: Identifiable {
    public var id: String { self }
}

内容的提问来源于stack exchange，提问作者hps28