Swift UI |文本字段未读取输入的值

问题描述

我有一个文本字段，应该记录某人食用的食品的单位，然后将其用于计算用户消耗的卡路里，蛋白质等的总数。但是，当在文本字段上输入值时，units变量不会更新。我该如何解决？

这是我的代码：

@State var selectFood = 0
@State var units = 0
@State var quantity = 1.0
    
@State var caloriesInput = 0.0
@State var proteinInput = 0.0
@State var carbsInput = 0.0
@State var fatsInput = 0.0

var body: some View {
    VStack {
        
        Group {
            Picker(selection: $selectFood,label: Text("What did you eat?")
                    .font(.title)
                    .fontWeight(.bold)
                    .foregroundColor(.white))
            {
                ForEach(database.productList.indices,id: \.self) { i in
                    Text(database.productList[i].name)
                }
            }
            .pickerStyle(MenuPickerStyle())
                
            Spacer(minLength: 25)
                
            Text("How much did you have?")
                .font(.headline)
                .fontWeight(.bold)
                .foregroundColor(.white)
                .frame(alignment: .leading)

            //Textfield not working.
            TextField("Units",value: $units,formatter: NumberFormatter())
                .padding(10)
                .background(Color("Settings"))
                .cornerRadius(10)
                .foregroundColor(Color("Background"))
                .keyboardType(.numberPad)
                
            Button (action: {
                self.quantity = ((database.productList[selectFood].weight) * Double(self.units)) / 100
                    
                caloriesInput = database.productList[selectFood].calories * quantity
                proteinInput = database.productList[selectFood].protein * quantity
                carbsInput = database.productList[selectFood].carbs * quantity
                fatsInput = database.productList[selectFood].fats * quantity
                    
                UIApplication.shared.hideKeyboard()
                    
            }) {
                ZStack {
                    Rectangle()
                        .frame(width: 90,height: 40,alignment: .center)
                        .background(Color(.black))
                        .opacity(0.20)
                        .cornerRadius(15)
                                    ;
                    Text("Enter")
                        .foregroundColor(.white)
                        .fontWeight(.bold)
                } 
            } 
        }
    }
}

解决方法

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