问题描述
最近我一直在尝试使用swiftui进行编程, 很难,如何将选择器的价值转移到 文本字段,我很拼命!
为什么我不能直接在文本字段中使用$ khValue值?
我已经花了数小时在互联网上搜索……我还没有发现任何东西,swiftUI与swift完全不同
import SwiftUI
struct KH_aus_Co2: View {
@State private var kh_Picker : String = ""
@State private var ph_Picker: String = ""
var kh_vol = [Int](0..<21)
var ph_vol = [Int](0..<10)
init(){
UITableView.appearance().backgroundColor = .clear
}
@State private var khWert: String = ""
@State private var phWert: String = ""
@State private var phco2Wert: String = ""
var calculation: String {
guard khWert.isEmpty == false,phWert.isEmpty == false else { return "" }
guard let kh = Double(khWert),let ph = Double(phWert) else { return "Error" }
let product = kh/2.8 * pow(10,7.90-ph)
return String(format: "%.2f",product)
}
var body: some View {
vstack() {
Text("Co2 = \(calculation) mg/ltr")
.font(.largeTitle)
.multilineTextAlignment(.center)
.foregroundColor(Color.green)
.frame(width: 300,height: 60,alignment: .center)
.border(Color.green)
.frame(minWidth: 0,maxWidth: .infinity,minHeight: 0,maxHeight: .infinity,alignment: .center)
HStack {
TextField("KH Wert",text: $khWert)
.border(Color.green)
.frame(width: 120,height: 70,alignment: .center)
.textFieldStyle(RoundedBorderTextFieldStyle())
// .textContentType(.oneTimeCode)
.keyboardType(.numberPad)
TextField("PH Wert",text: $phWert)
.border(Color.green)
.frame(width: 120,alignment: .center)
.textFieldStyle(RoundedBorderTextFieldStyle())
// .textContentType(.oneTimeCode)
.keyboardType(.numberPad)
}
GeometryReader { geometry in
HStack {
Picker(selection: self.$kh_Picker,label: Text("")) {
ForEach(0 ..< self.kh_vol.count) { index in
Text("\(self.kh_vol[index])").tag(index)
//
}
}
.frame(width: geometry.size.width/3,height: 100,alignment: .center) .clipped()
Picker(selection: self.$ph_Picker,label: Text("")) {
ForEach(0 ..< self.ph_vol.count) { index in
Text("\(self.ph_vol[index])").tag(index)
}
}
.frame(width: geometry.size.width/3,alignment: .center) .clipped()
}
}
}
.navigationBarTitle(Text("Co2 aus KH & PH"))
.font(/*@START_MENU_TOKEN@*/.title/*@END_MENU_TOKEN@*/)
}
}
struct KH_aus_Co2_Previews: PreviewProvider {
static var previews: some View {
Co2_aus_KH()
}
}
非常感谢您的帮助
尤尔根(Jürgen)....................................
解决方法
如果我对您的理解正确,那么您希望选择器更新文本字段中的值。如果是这样,则您要将相同的值绑定到文本字段正在使用的选择器。由于该值是String
,因此您将需要在选择器中使用String
值。
使用.map(String.init)
将kh_vol
和ph_vol
范围转换成String
的数组,并使用\.self
作为id:
:>
Picker(selection: self.$khWert,label: Text("")) {
ForEach(self.kh_vol.map(String.init),id: \.self) { index in
Text(index)
}
}
.frame(width: geometry.size.width/3,height: 100,alignment: .center)
.clipped()
Picker(selection: self.$phWert,label: Text("")) {
ForEach(self.ph_vol.map(String.init),alignment: .center)
.clipped()