Setting a boolean in swiftui with if statement

Question

I'm very new to swiftui so I don't know if I'm doing completely wrong but the error is not helpful. Here is my code:

import SwiftUI

struct IntroScreenP2: View {
 var hasName: Bool = false
 @State private var firstName: String = ""
 @State private var lastName: String = ""
 var body: some View {
  VStack {
   if firstName != "" && lastName != "" {
    hasName = true
   }
   TextField("First Name", text: $firstName)
    .padding(.leading)
    .padding(.bottom, 5)
   Divider()
   TextField("Last Name", text: $lastName)
    .padding(.leading)
    .padding(.top, 5)
   }
  }
}

I'm just trying to set a boolean equal to true when the user enters their name in the text field. It keeps giving me an error saying "Type of expression is ambiguous without more context"

Chris · Accepted Answer · 2019-12-08 20:12:15Z

1

you cannot just "code" as usual in SwiftUI. SwiftUI requires that you return Views. Maybe you should read some Introduction and Tutorials to SwiftUI.

Here is the code "corrected". If you tell me what you want with your variable i can help you further more.

struct ContentView: View {
    @State var hasName: Bool = false
    @State private var firstName: String = ""
    @State private var lastName: String = ""
    var body: some View {
        VStack {
            if firstName != "" && lastName != "" {
              Text("Has name")
            }
            TextField("First Name", text: $firstName)
                .padding(.leading)
                .padding(.bottom, 5)
            Divider()
            TextField("Last Name", text: $lastName)
                .padding(.leading)
                .padding(.top, 5)
        }
    }
}

answered Dec 8, 2019 at 20:12

Chris

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1 Comment

Alexander Over a year ago

It would be incorrect to define hasName with @State. @State introduces a new source of truth, whereas here it should be a derived value, computed from firstName and lastName. This could be done by either making it a computed property, or by using didSet observers on firstName and lastName to update it after every change.

Mojtaba Hosseini · Accepted Answer · 2019-12-08 20:26:46Z

1

You don't need to set it at all! Just make it computed:

var hasName: Bool { firstName != "" && lastName != "" }

Note that it's better to use .isEmpty instead:

var hasName: Bool { !firstName.isEmpty && !lastName.isEmpty }

answered Dec 8, 2019 at 20:26

Mojtaba Hosseini

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