Swift UI |文本字段未读取输入的值
Swift UI | Textfield not reading entered value
我有一个文本字段,它应该记录某人吃过的食品的单位,然后用于计算用户消耗的卡路里、蛋白质等的总数。但是当在文本字段中输入值时,units
变量不会更新。我该如何解决这个问题?
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)
}
}
}
}
}
这是 NumberFormatter
的一个问题,已经持续了一段时间。如果您删除格式化程序,它会正确更新。
这是一种解决方法。遗憾的是它需要 2 个变量。
import SwiftUI
struct TFConnection: View {
@State var unitsD: Double = 0
@State var unitsS = ""
var body: some View {
VStack{
//value does not get extracted properly
TextField("units", text: Binding<String>(
get: { unitsS },
set: {
if let value = NumberFormatter().number(from: [=10=]) {
print("valid value")
self.unitsD = value.doubleValue
}else{
unitsS = [=10=]
//Remove the invalid character it is not flawless the user can move to in-between the string
unitsS.removeLast()
print(unitsS)
}
}))
Button("enter"){
print("enter action")
print(unitsD.description)
}
}
}
}
struct TFConnection_Previews: PreviewProvider {
static var previews: some View {
TFConnection()
}
}