Auto hidden keyboard after enter six characters

Question

I am a swift beginner. I implemented this functionality in ViewController, but I don't want to write such code in every ViewController. I want to implement it through a protocol, but something is wrong.

import UIKit

@objc protocol TextFieldAutoHiddenKeyboard: class {
    var textFieldAutoHidenLenth: UInt {get set} 
}

extension TextFieldAutoHiddenKeyboard where Self: UIViewController {

    func autoHiddenKeyboardWhenFillUpTextFiled(textField textF: UITextField, autoHidenLenth: UInt) {
        textFieldAutoHidenLenth = autoHidenLenth

        let textFieldDidChangeActionName = "textFieldDidChange(textField:)"
        let textFieldDidChangeAction = Selector(textFieldDidChangeActionName)
        textF.addTarget(self, action: textFieldDidChangeAction, for: .editingChanged)

        let dismissKeyboardActionName = "dismissKeyboard"
        let dismissKeyboardAction = Selector(dismissKeyboardActionName)
        let tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: dismissKeyboardAction)
        view.addGestureRecognizer(tap)
      //textF.addTarget(self, action: #selector(textFieldDidChange(textField:autoHidenLenth:)), for: .editingChanged)
    }

    func textFieldDidChange(textField: UITextField) {
        if let text = textField.text {
            if text.count == textFieldAutoHidenLenth {
                textField.resignFirstResponder()
            }
        }
    }

    func dismissKeyboard() {
        view.endEditing(true)
    }

    //@objc func textFieldDidChange(textField: UITextField, autoHidenLenth: UInt) {
    //    if let text = textField.text {
    //        if text.count == autoHidenLenth {
    //           textField.resignFirstResponder()
    //        }
    //    }
    //}
}

Why my app crash. EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
By creating an Action using a Selector, #selector(textFieldDidChange(textField:autoHidenLenth:)), I don't know how to pass the second argument to function. For example, the parameter autoHidenLenth.
How to implement this function correctly through Protocol?

_{(source: recordit.co)}

You need to just take TextField delegate method and check inputted length of greater than 6 or is is not backspace character then don't allow to add it to textfield. — PiyushRathi, Aug 08 '18 at 05:37
You don't need any of this code. Just subclass viewController and try what i have posted as an answer. — Rakesha Shastri, Aug 08 '18 at 06:04
@Lal Krishna and @Rakesha Shastri answer is really helping me. I try to implement this function using the delegate method ` func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool { } `.I think it is very unsatisfactory. Don't forget that users may paste content through the phone clipboard. — UninhibitedSoul, Aug 08 '18 at 07:30
You can prevent the user's copy paste from working if the result is more than 6 characters. I have updated my answer with this logic. — Rakesha Shastri, Aug 08 '18 at 08:58

Taimoor Suleman · Answer 1 · 2018-08-08T05:51:57.440

0

You have to implement a delegate method for this:

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
         let  char = string.cString(using: String.Encoding.utf8)!
    let isBackSpace = strcmp(char, "\\b")

    if (isBackSpace == -92) {
        print("Backspace was pressed")
        return true
    }
    if((textField.text?.length)! == 6){
        self.view.endEditing(true)
        return true
    }
    return true
    }

and dont forget to assign Delegate

textfield.delegate = self

edited Aug 08 '18 at 05:51

answered Aug 08 '18 at 05:46

Taimoor Suleman

1,588
14
29

This will dismiss the keyboard when the user enters the seventh character not after the sixth. – Rakesha Shastri Aug 08 '18 at 05:47

score 0 · Answer 2 · answered Aug 08 '18 at 05:48

0

You are using wrong delegate of textfield. you should use delegate of textfield which is respond on change of character not field change.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    let length = (yourtextfield.text?.characters.count)! - range.length + string.characters.count
    if length == 6 {

       yourtextfield.resignFirstResponder()
        return true

    }else {
        return true
    }    
}

answered Aug 08 '18 at 05:48

Rakesh Patel

1,673
10
27

OP clearly wants the textField dismissed after the sixth character has been entered. So he is using the right delegate. This is wrong. – Rakesha Shastri Aug 08 '18 at 05:51
As @RakeshaShastri say,I wants the textField dismissed after the sixth character has been entered. I try you code.[Test you code](http://g.recordit.co/sstEUUkHXb.gif). And [This is I want](http://g.recordit.co/JhyTVQSkTr.gif). – UninhibitedSoul Aug 08 '18 at 06:48
@ UninhibitedSoul just change length == 6 to 7 and you will get your desired output. – Rakesh Patel Aug 08 '18 at 06:57
@ Rakesh Patel I don't think so.Imagine if you have a six-digit verification code, would you enter one more number after entering the verification code? This is unreasonable – UninhibitedSoul Aug 08 '18 at 07:34
@ UninhibitedSoul its depend on your requirement. I only write a code to dismiss keyboard after a 6 character get by textfield. – Rakesh Patel Aug 08 '18 at 07:58

score 0 · Answer 3 · answered Aug 08 '18 at 05:49

0

You should not construct the selector with a string literal but rather use #selector(textFieldDidChange(textField:)), then you will see that a selector method needs to be exposed to Objective C.
Thus you should be able to fix it by writing:

@objc func textFieldDidChange(textField: UITextField) {
    if let text = textField.text {
        if text.count == textFieldAutoHidenLenth {
            textField.resignFirstResponder()
        }
    }
}

answered Aug 08 '18 at 05:49

Robin M.

96
1
5

As for the second / third problem: why don't you create a subclass rather than a protocol for this functionality? – Robin M. Aug 08 '18 at 05:53

score 0 · Accepted Answer · answered Aug 08 '18 at 06:20

As you need to enable this feature for multiple textfields, you can use this.

References: Link1, Link2

private var autoHiddenLengthAssociationKey: UInt8 = 0

extension UITextField {

    private var autoHiddenLenth: Int? {
        get {
            return objc_getAssociatedObject(self, &autoHiddenLengthAssociationKey) as? Int
        }
        set {
            objc_setAssociatedObject(self, &autoHiddenLengthAssociationKey, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_ASSIGN)
        }
    }

    func enableAutoHidingFeature(maxLength: Int) {
        autoHiddenLenth = maxLength
        self.addTarget(self, action: #selector(textDidChange(textField:)), for: .editingChanged)
    }

    @objc func textDidChange(textField: UITextField) {

        guard let maxLength = autoHiddenLenth, let text = textField.text else { return }

        if text.count == maxLength {
            textField.resignFirstResponder()
        }
    }
}

You can enable this by calling:

textField.enableAutoHidingFeature(maxLength: 6)

Glad to help. Can you accept this answer so it may be helpful for someone else in future. — Lal Krishna, Aug 08 '18 at 07:04

Auto hidden keyboard after enter six characters

4 Answers4