How to validate if Textfield is empty?

Question

Good night, my friends

I am having difficulty in the following, I intend that the user receive a warning when the textfield is empty and if it pressed the button.

tried with the if condition (textFiel.text == "") but it didn’t work out, thanks for our help.

@IBAction func botton(_ sender: Any) {

    let celcius = Float(textFiel.text!)!
    let Fahrenheit:Float = (9 * celcius + 160) / 5
    label.text = "\(Fahrenheit)"


    if (textFiel.text == "") {
        label.text = "Por favor digite algo"
    }

}

Answer 1

Another suggestion is to use the command Guard:

@IBAction func botton(_ sender: Any) {

    guard !((textField.text ?? "").isEmpty) else {
        label.text = "Por favor digite algo"
        return
    }
    let celcius = NSString(string: textField.text!).floatValue
    let Fahrenheit:Float = (9 * celcius + 160) / 5
    label.text = "\(Fahrenheit)"
}

Answer 2

I suggest you use the guard let, force ! is not a good practice.

guard let text = textField.text, !text.isEmpty else {
    return
}

Answer 3

I think the idea is to check, besides if the text is empty, if it is not nil...

if textFiel.text != nil && !textFiel.text.isEmpty {
   label.text = "Por favor, digite algo"
}

Answer 4

Your code is comparing the objecto textFiel with the empty string (""). What you want, is to compare if the property text of the textFiel object contains or does not contain any text.

This can be done as follows:

if (let texto = textFiel.text, !texto.isEmpty)

Perhaps it would be better to carry out this validation before making the calculation:

@IBAction func botton(_ sender: Any) {

    if let texto = textFiel.text, !texto.isEmpty 
    {
        let celcius = Float(textFiel.text!)!
        let Fahrenheit:Float = (9 * celcius + 160) / 5
        label.text = "\(Fahrenheit)"
    else
    { 
        label.text = "Por favor digite algo"

    }
}

See the example