How can i make a TextField validation work in SwiftUI?-CodePudding

I have a little problem and I do not know how can I fix it .

I have a textfield, and when the textfield does not meet a certain criteria, I want to display a text underneath. All is working fine, except that the error text underneat is displayed just when the view is reloaded, like exit from the view and entering again.

I will put the code below so you can look at it :

struct EntryField: View {
    var placeHolder: String
    var prompt: String
    @Binding var field: String
    var body: some View {
        VStack(alignment: .leading) {
         TextField(placeHolder, text: $field).autocapitalization(.none)
            Text(prompt)
        }
    }
}

class VerifyFieldsViewModel : ObservableObject {
    
    @ObservedObject var coreDataViewModel = CoreDataViewModel()
    func isValid() -> Bool {
        guard coreDataViewModel.savedDetails.first?.firstName?.count ?? 0 > 0 else {
            return false
        }
        return true
    }
    
    var isFirstNameValid : String {
        if isValid() {
       return ""
        
        } else {
        return "Complete first name"
        }
    }
}

@available(iOS 15.0, *)
struct DeliveryView: View {
    @ObservedObject var verifyFieldsViewModel = VerifyFieldsViewModel()
    @StateObject var coreDataViewModel = CoreDataViewModel()
    var body: some View {
        let firstName = Binding(
            get: {coreDataViewModel.savedDetails.first?.firstName ?? ""},
            set: {coreDataViewModel.savedDetails.first?.firstName = $0})

        ScrollView {
            VStack(alignment: .leading) {
               
                    Text("Nume")
                        .foregroundColor(.orange)
                    EntryField(placeHolder: "Popescu", prompt: verifyFieldsViewModel.isFirstNameValid , field: firstName)
                        .onSubmit {
                            coreDataViewModel.saveContext()
                        }
        }
       
    }
}
}

That's the code. Hope you can help me with this problem. Thank you !!

CodePudding user response：

Well since you need to frequently update the error message then your prompt property in EmptyField should be Binding, otherwise you'll need to refresh the view.

@Binding var prompt: String

Or you can directly use the model in EmptyField, full code:

struct EntryField: View {
    var placeHolder: String
    @ObservedObject var verifyFieldsViewModel: VerifyFieldsViewModel //edited here
    @Binding var field: String
    var body: some View {
        VStack(alignment: .leading) {
            TextField(placeHolder, text: $field).autocapitalization(.none)
            Text(verifyFieldsViewModel.isFirstNameValid) //edited here
        }
    }
}

class VerifyFieldsViewModel : ObservableObject {
    @ObservedObject var coreDataViewModel = CoreDataViewModel()
    func isValid() -> Bool {
        guard coreDataViewModel.savedDetails.first?.firstName?.count ?? 0 > 0 else {
            return false
        }
        return true
    }
    var isFirstNameValid : String {
        if isValid() {
            return ""
        }else {
            return "Complete first name"
        }
    }
}

@available(iOS 15.0, *)
struct DeliveryView: View {
    @ObservedObject var verifyFieldsViewModel = VerifyFieldsViewModel()
    @StateObject var coreDataViewModel = CoreDataViewModel()
    var body: some View {
        let firstName = Binding(
            get: {coreDataViewModel.savedDetails.first?.firstName ?? ""},
            set: {coreDataViewModel.savedDetails.first?.firstName = $0})
        ScrollView {
            VStack(alignment: .leading) {
                Text("Nume")
                    .foregroundColor(.orange)
                EntryField(placeHolder: "Popescu", verifyFieldsViewModel: verifyFieldsViewModel, field: firstName) //edited here
                    .onSubmit {
                        coreDataViewModel.saveContext()
                    }
            }
        }
    }
}