检查UITextField是否为空或是否在viewDidLoad上启用按钮

Question

I have mutiple UItextFields in a ViewController. Also I have outlet functions from storyboard to check if the textfields are empty or not and I am enabling a button only when the textfields are non-empty.

For a few of the textfields I am setting the data before viewDidLoad so the user does not have to manually enter it. Even though these textfields have data, they have to be clicked once so that button gets enabled.

var isFirstNameValid = false
@IBAction func validateFirstName(sender: AnyObject) {
        guard (!firstNameText.text!.isEmpty) else{
            isFirstNameValid = false
            return
        }
        isFirstNameValid = true
        enableRegisterButton()
    }


func enableRegisterButton()
    {
        guard (isFirstNameValid) else{
            registerButton.enabled = false
            return
        }
        registerButton.enabled = true
    }

I want to enable the button when the textfield has data entered by the user or programatically set before viewDidLoad method.

Answer 1

Your code seems be good, but i think you need to try to replace this:

@IBAction func validateFirstName(sender: AnyObject) {
    guard (!firstNameText.text!.isEmpty) else{
        isFirstNameValid = false
        return
    }
    isFirstNameValid = true
    enableRegisterButton()
}

by

@IBAction func validateFirstName(sender: AnyObject) {
    isFirstNameValid = !firstNameText.text!.isEmpty
    enableRegisterButton()
}

OR:

You can check in your connections inspector for a Value Changed event and add the method.

Even if it's not working, you can check for your data value in the viewWillAppear() method:

override func viewWillAppear(animated: Bool) {
    registerButton.enabled = !firstNameText.text!.isEmpty
}

Answer 2

Try this. But as you say "when the textfield has data entered by the user" so you can't do it before viewDidLoad.I think you should explain more.

textField.addTarget(self, action: #selector(YourViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

and

func textFieldDidChange(textField: UITextField) {
    //your code.enable your button here
}

Answer 3

Validate all the the textfields once in viewDidLoad() and try to enable register button. This way register button will be enabled even if all of the textfields are pre-filled without requiring you to click any of them Like this:

isFirstNameValid = !firstNameText.text!.isEmpty
isLastNameValid = !lastNameText.text!.isEmpty
// rest of the fileds...
enableRegisterButton()

Answer 4

Your validation code needs to run without user interaction and the best place to do this is in viewDidLoad . Create a checker function which takes in a UITextField as its argument and does the actual checking. This way, you can call that checker function in viewDidLoad as well as later on when you validate actual user input in your IBAction or wherever.

override func viewDidLoad() {
    super.viewDidLoad()

    // This is where your code to set firstNameText goes

    let isFirstNameValid = checker(firstNameText)

    myButton.enabled = false
    if isFirstNameValid { registerButton.enabled = true }
}

func checker(textField: UITextField) -> Bool {
    guard (!textField.text!.isEmpty) else {
        return false
    }
    return true
}

---

Side Note

The enableRegisterButton() function is extraneous. You've already done the checking which is what called the function to begin with, so checking if the first name is valid inside the enableRegisterButton is redundant. The only useful line in that function is registerButton.enabled = true , which we can write without using the function at all.