如何创建一个选择器（选择一个人的体重和身高）来根据其区域设置显示英制/公制测量值？

Question

我对 SwiftUI 很陌生。我正在创建一个选择器，它可以让用户选择他们的体重（以及类似的身高）。如您所知，在美国（和其他一些国家），人们使用英制单位（磅、英尺等），而在大多数其他国家，人们使用公制（公斤、米等）。如何使该选择器轻松准确地适应用户的区域/区域设置？例如，如果用户所在地区使用公制，则显示[40kg, 42.5kg, 45kg, 47.5kg, .... 300kg]；如果是英制，则显示 [80lb, 85lb, 90lb, ..., 600lb]

这是我的代码草案，基本上硬编码了英制测量的内容：

import SwiftUI

struct SetMyWeightView: View {
    
    // This works for imperial system. But how I can make it work for both imperial and metric system? For example, if user's region uses metric system, display [40kg, 42.5kg, 45kg, 47.5kg, .... 300kg]; if imperial, display [80lb, 85lb, 90lb, ..., 600lb]

    @State private var myWeight: Int?
    
    var body: some View {
        Form {
            Section {
                Picker("", selection: $myWeight) {
                        // Offer user an option to hide their weight
                        Text("Hide").tag(nil as Int?)
                    
                        // Choose from a list [80, 85, 90, ..., 600]
                        ForEach(Array(stride(from: 80, to: 601, by: 5)), id: \.self) { weight in
                            Text("\(weight) lb").tag(weight as Int?)
                        }
                }
                .pickerStyle(.wheel)
            } header: {
                Text("Weight")
            }
        }
    }
}

#Preview {
    SetMyWeightView()
}

Answer 1

您可以通过使用 Locale.current 类来实现这一点。其中有两个属性（其中之一是在 iOS 16 中引入的，它告诉您设备采用哪种公制系统。代码如下：

struct SetMyWeightView: View {
    
    
    var isMetric: Bool {
        let locale = Locale.current
        if #available(iOS 16, *) {
            return locale.measurementSystem == .metric
        } else {
            return locale.usesMetricSystem
        }
        
    }
    
    var weightUnit: String {
        return isMetric ? "kg" : "lb"
    }
    
    var weightRange: ClosedRange<Int> {
        return isMetric ? 40...300 : 80...600
    }
    
    @State private var myWeight: Int?
    
    var body: some View {
        Form {
            Section {
                Picker("", selection: $myWeight) {
                    // Offer user an option to hide their weight
                    Text("Hide").tag(nil as Int?)
                    
                    ForEach(Array(stride(from: weightRange.lowerBound, through: weightRange.upperBound, by: 5)), id: \.self) { weight in
                        Text("\(weight) \(weightUnit)").tag(weight as Int?)
                    }
                }
                .pickerStyle(.wheel)
            } header: {
                Text("Weight")
            }
        }
    }
}

尝试一下，让我知道这是否适合您！