SwiftUI开发求助：将CoreML模型计算的理想就寝时间固定显示在顶部

要将计算出的理想就寝时间固定显示在界面顶部，只需对现有代码做以下几点修改：

• 添加状态变量存储计算结果
• 在界面顶部增加结果展示区域
• 调整计算逻辑，将结果赋值给状态变量而非弹窗展示

修改后的完整代码： #

import CoreML
import SwiftUI

struct ContentView: View {
    @State private var wakeUp = defaultWakeUpTime
    @State private var sleepAmount = 8.0
    @State private var coffeeAmount = 1
    
    @State private var alertTitle = ""
    @State private var alertMessage = ""
    @State private var showingAlert = false
    // 新增：存储理想就寝时间的状态变量
    @State private var idealBedtime: Date?
    
    static var defaultWakeUpTime: Date {
        var components = DateComponents()
        components.hour = 7
        components.minute = 0
        return Calendar.current.date(from: components) ?? Date.now
    }
    
    var body: some View {
        NavigationView {
            VStack(spacing: 0) {
                // 新增：顶部固定展示理想就寝时间的区域
                if let bedtime = idealBedtime {
                    HStack {
                        Text("你的理想就寝时间")
                            .font(.subheadline)
                            .foregroundColor(.secondary)
                        Spacer()
                        Text(bedtime.formatted(date: .omitted, time: .shortened))
                            .font(.title)
                            .fontWeight(.bold)
                    }
                    .padding()
                    .background(Color(.systemGray6))
                }
                
                Form {
                    Section() {
                        Text("你打算几点起床？")
                            .font(.headline)
                        
                        DatePicker("请选择时间", selection: $wakeUp, displayedComponents: .hourAndMinute)
                            .labelsHidden()
                    }
                    
                    Section() {
                        Text("期望睡眠时间")
                            .font(.headline)
                        
                        Stepper("\(sleepAmount.formatted()) 小时", value: $sleepAmount, in: 4...12, step: 0.25)
                    }
                    
                    Section() {
                        Text("每日咖啡摄入量")
                        Picker("杯数", selection: $coffeeAmount) {
                            ForEach(1..<21) {
                                Text("\($0) 杯")
                            }
                        }
                        .pickerStyle(.wheel)
                    }
                }
            }
            .navigationTitle("优质睡眠助手")
            .toolbar {
                Button("计算", action: calculateBedTime)
            }
            .alert(alertTitle, isPresented: $showingAlert) {
                Button("确定") { }
            } message: {
                Text(alertMessage)
            }
        }
    }
    
    func calculateBedTime() {
        do {
            let config = MLModelConfiguration()
            let model = try SleepCalculator(configuration: config)
            
            let components = Calendar.current.dateComponents([.hour, .minute], from: wakeUp)
            let hour = (components.hour ?? 0) * 60 * 60
            let minute = (components.minute ?? 0) * 60
            
            let prediction = try model.prediction(wake: Double(hour + minute), estimatedSleep: sleepAmount, coffee: Double(coffeeAmount))
            
            let sleepTime = wakeUp - prediction.actualSleep
            // 将结果赋值给状态变量，而非弹窗
            idealBedtime = sleepTime
        } catch {
            alertTitle = "错误"
            alertMessage = "抱歉，计算就寝时间时出现问题。"
            showingAlert = true
        }
    }
}

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

关键修改说明： #

1. 新增状态变量：@State private var idealBedtime: Date? 用于存储计算后的就寝时间，初始值为nil表示未计算。
2. 顶部展示区域：通过if let bedtime = idealBedtime判断是否已计算，若有结果则在Form上方显示一个带背景的信息栏，用加粗字体突出显示时间。
3. 调整计算逻辑：在calculateBedTime函数中，成功计算后将结果赋值给idealBedtime，不再触发弹窗；错误情况仍保留弹窗提示。

内容的提问来源于stack exchange，提问作者Hamza