【发布时间】：2020-11-22 08:35:18
【问题描述】：
我正在尝试从调用该视图的视图访问在视图中标记为@State 的变量。子视图中的这些变量连接到一个文本框。如果我在该文本框中键入并按回车键，然后单击一个按钮，则该按钮位于父视图中，要读取该变量，它会返回一个空字符串。如果我拿那个按钮并将它放在子视图中并做同样的事情，它会打印我在文本框中输入的内容。我对 SwiftUI 很陌生，这可能是一个非常简单的修复方法，但我已经尝试了所有方法。非常感谢任何帮助！
父视图（DetailedView）
struct DetailedView: View {
@Environment(\.managedObjectContext) var moc
var targetMuscle : String = "Chest"
let today = Date()
@State public var exerciseCards : [ExerciseCard] = []
@State public var exercise : String = "Bench Press"
@State public var exercises : Int = 0
@State public var showPassedWorkouts : Bool = false
static let taskDateFormat : DateFormatter = {
let formatter = DateFormatter()
formatter.dateStyle = .long
return formatter
}()
var body: some View {
ZStack{
VStack{
HStack{
VStack{
Text(targetMuscle).font(.system(size:40)).fontWeight(.medium)
Text("\(today, formatter: Self.taskDateFormat)")
.font(.system(size:20))
}.frame(width: 250, height: 30, alignment: .topLeading)
.navigationBarTitle("")
.navigationBarHidden(true)
.padding(.bottom, -7)
Button(action: {
self.showPassedWorkouts.toggle()
}) {
Text("Passed Workouts")
.multilineTextAlignment(.center)
}.offset(x: -75, y: 25)
.sheet(isPresented: $showPassedWorkouts){
PassedWorkoutList()
}
Button(action: {
let workout = Workout(context: self.moc)
workout.muscle = self.targetMuscle
workout.date = formattedDateString(day: self.today)
for number in 0..<self.exerciseCards.count{
let exercise = Exercise(context: self.moc)
exercise.name = self.exerciseCards[number].exercise
for innerNum in 0..<self.exerciseCards[number].tableRows.count{
let exerciseSet = ExerciseSet(context: self.moc)
exerciseSet.reps = Int16(self.exerciseCards[number].tableRows[innerNum].reps) ?? 0
exerciseSet.weight = Int16(self.exerciseCards[number].tableRows[innerNum].weight) ?? 0
exerciseSet.set = self.exerciseCards[number].tableRows[innerNum].set
exercise.addToExerciseSet(exerciseSet)
}
workout.addToExercise(exercise)
}
try? self.moc.save()
}) {
Text("Finish")
}.offset(x: -20, y: 20)
}.padding(.bottom, 35)
.padding(.leading)
ScrollView{
ForEach(0..<exerciseCards.count, id: \.self){ number in
self.exerciseCards[number]
}
Button(action: {
self.exerciseCards.append(ExerciseCard())
}) {
Text("Add Exercise")
.frame(minWidth: 325)
.padding()
.foregroundColor(.white)
.background(Color.blue.opacity(0.7))
.cornerRadius(20)
}.padding(.top)
.frame(width: 400)
}
}
}.background(Color.white)
}
}
第一个子视图（ExerciseCard）
struct ExerciseCard: View {
@State public var exercise : String = ""
@State public var tableRows : [ExerciseTableRow] = []
var body: some View {
VStack{
TextField("Enter Exercise", text: $exercise).textFieldStyle(RoundedBorderTextFieldStyle())
.frame(width: 300)
.multilineTextAlignment(.center)
HStack{
Group{
Text("Set")
Text("Weight")
Text("Reps")
}.padding(.horizontal, 30)
.offset(x: -20, y: 0)
}
VStack{
ForEach(0..<tableRows.count, id: \.self){ number in
self.tableRows[number]
}
}.padding(.bottom, 5)
HStack{
Button(action: {
if self.tableRows.count > 1{
self.tableRows.remove(at: self.tableRows.count-1)
}
}) {
Text("Remove Set")
.frame(minWidth: 150)
.padding(.vertical, 5)
.foregroundColor(.white)
.background(Color.red)
.cornerRadius(20)
}
Button(action: {
self.tableRows.append(ExerciseTableRow(set: 2, readOnly: false, setWeight: 2, setReps: 2))
}) {
Text("Add Set")
.frame(minWidth: 150)
.padding(.vertical, 5)
.foregroundColor(.white)
.background(Color.green)
.cornerRadius(20)
}
}
}
.padding()
.padding(.vertical)
.background(Color.offWhite)
.cornerRadius(20)
.shadow(color: Color.black.opacity(0.2), radius: 10, x:10, y:10)
.shadow(color: Color.white.opacity(0.7), radius: 10, x:-5, y:-5)
}
}
第二个子视图（ExerciseTableRow）
struct ExerciseTableRow: View {
@State public var weight : String = "0"
@State public var reps : String = "0"
var set : Int16
var readOnly : Bool
var setWeight : Int16
var setReps : Int16
var body: some View {
HStack{
Text(String(set))
.padding(.trailing, 40)
.padding(.leading, 10)
if readOnly == false{
Group{
TextField("0", text: $weight)
TextField("0", text: $reps)
}.textFieldStyle(RoundedBorderTextFieldStyle())
.frame(width: 50)
.multilineTextAlignment(.center)
.keyboardType(.numberPad)
.padding(.horizontal, 30)
}
else{
Group{
Text(String(setWeight))
Text(String(setReps))
}
.frame(width: 50)
.overlay(
RoundedRectangle(cornerRadius: 5)
.stroke(Color.black, lineWidth: 1)
)
.padding(.bottom, 5)
.padding(.horizontal, 30)
}
}
}
}
【问题讨论】：