How to implement a fully functional backspace key in custom keyboard button swift

Question

How do you implement a custom backspace/delete button for a custom keyboard in iOS that responds to a UITextField delegate in swift?

check this: http://stackoverflow.com/questions/28024197/how-to-create-a-button-that-have-same-functionality-as-apple-original-keyboard-b/28107466#28107466 — Dharmesh Kheni, Jan 29 '15 at 11:11

Tyler Durden · Accepted Answer · 2015-01-29T15:06:35.680

I was struggling with this for a while so thought i would answer the question. The following code responds to a custom backspace key being pressed on a uikeyboard that is a first responder to a UITextfield:

// the tag for the backspace button
if tag == "<"{
        //the range of the selected text (handles multiple highlighted characters of a uitextfield)
        let range = textField.selectedTextRange?;

        // if the range is empty indicating the cursor position is 
        // singular (no multiple characters are highlighted) then delete the character 
        // in the position before the cursor
        if range!.empty {

            let start = textField.positionFromPosition(range!.start, offset: -1);
            let end = axiomBuilderTV.positionFromPosition(range!.end, offset: 0);
            axiomBuilderTV.replaceRange(axiomBuilderTV.textRangeFromPosition(start, toPosition: end), withText: "");
        }
        // multiple characters have been highlighted so remove them all
        else {
            textField.replaceRange(range!, withText: "");
        }

    }

score 2 · Answer 2 · edited Mar 01 '15 at 15:11

2

You may find global method "droplast()" to be a great help.(also there is a "dropfirst")

var stringToBeBackspace = "abcde"
dropLast(stringToBeBackspace)    //.swift

String is actually a collection of characters, so you can also do slide character in a string which you may find "countElements" to be a great help.

edited Mar 01 '15 at 15:11

Rizier123

58,877
16
101
156

answered Mar 01 '15 at 14:55

Leffison

61
5

score 1 · Answer 3 · answered Mar 16 '16 at 14:50

1

I now this question has been answered long ago, But I would like to shared my approach based on UIKeyInput (tested on iOS9 and Xcode 7- Swift 2).

    @IBAction func backspacePressed(btn: UIButton) {
        if btn.tag == 101 {

            (textDocumentProxy as UIKeyInput).deleteBackward()
        }
    }

answered Mar 16 '16 at 14:50

Carlos

963
9
19

1

what is textDocumentProxy ? – Varun Naharia Mar 08 '18 at 10:11

score 0 · Answer 4 · answered Mar 20 '17 at 09:37

Swift 3.0.1

This answer reacts to backspace/delete button but has the extra feature of limiting maximum number of characters that can be typed into a textField. So if the textField contained more characters than the maximum number because a string inserted programmatically into a textField you cannot add characters but you can delete them because 'range.length' returns 1 only with the delete key.

Thanks go to OOPer for the original code which limits number of characters. https://forums.developer.apple.com/thread/14627

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool { // Updates everytime character ie typed or deleted until Max set in textFieldLimit
    let textFieldLimit = 30
    if (range.length == 1) { // Delete button = 1 all others = 0
        return true
    } else {
        return (textField.text?.utf16.count ?? 0) + string.utf16.count - range.length <= textFieldLimit
    }
}

How to implement a fully functional backspace key in custom keyboard button swift

4 Answers4