How do I get the last n characters typed in a UITextView?

Question

Say I want to check if the last 5 characters typed in a UITextView are "mouse". How would I go about doing this? Specifically in Swift because of how strings indexes are different from Objective-C due to how emojis and the like are stored.

I cannot seem to figure this out. And keep in mind the last n characters may not be typed at the end of the text view, the cursor could be in the middle of the text.

NSString *trimmedString=[textfield.text substringFromIndex:MAX((int)[string length]-5, 0)]; //in case string is less than 5 characters long. — Saurabh Prajapati, Jun 30 '15 at 04:26
take look at http://stackoverflow.com/questions/6591538/how-to-capture-last-4-characters-from-nsstring — Saurabh Prajapati, Jun 30 '15 at 04:27
is it a requirement that the characters be contiguous? or are you simply asking "how do I keep track of the last 5 keystrokes, no matter where they occurred in the text view"? — fqdn, Jun 30 '15 at 04:30
Hey Doug, I know this is an old question, but if could check my answer works for you, I'd really appreciate it. — OrderAndChaos, Sep 16 '16 at 18:05

OrderAndChaos · Answer 1 · 2016-09-12T15:42:35.660

This function will return the last n characters from the last cursor position in the textView, unless the cursor position is too close to the start of the string, in which case it will return from the start of the string to the cursor.

To check on each change make the ViewController a delegate of UITextViewDelegate and implement textViewDidChange()

class ViewController: UIViewController, UITextViewDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        textView.delegate = self
    }

    func textViewDidChange(textView: UITextView) {
        print(lastNChars(5, textView: textView)!)
    }

    func lastNChars(n: Int, textView: UITextView) -> String? {
        if let selectedRange = textView.selectedTextRange {
            let startPosition: UITextPosition = textView.beginningOfDocument
            let cursorPosition = textView.offsetFromPosition(startPosition, toPosition: selectedRange.start)
            let chars = textView.text as String
            var lastNChars: Int!
            if n > cursorPosition {
                lastNChars = cursorPosition
            } else {
                lastNChars = n
            }
            let startOfIndex = chars.startIndex.advancedBy(cursorPosition - lastNChars)
            let endOfIndex = chars.startIndex.advancedBy(cursorPosition)
            let lastChars = chars.substringWithRange(startOfIndex ..< endOfIndex)
            return lastChars
        }
        return nil
    }
}

@araferna Long time since I looked at this. The count is from the last cursor position not the end of the string it doesn't matter where the user types as far as I recall. — OrderAndChaos, Jun 12 '20 at 14:49

score 0 · Answer 2 · answered Jun 30 '15 at 04:55

0

You can use substringFromIndex with textView.text.. Thus the last 5 characters can be obtained by this code.

let strLast5: String =  textView.text.substringToIndex(countElements(textView.text) - 5);

answered Jun 30 '15 at 04:55

Sudhin Davis

2,010
13
18

Per my second paragraph it's not at the end necessarily? – Doug Smith Jun 30 '15 at 17:01
Oh.. That was not my chance then.. Sorry, For that yopu must go for shouldChangeTextInRange delegate method. – Sudhin Davis Jul 01 '15 at 03:51

score 0 · Answer 3 · answered Jan 21 '19 at 07:20

0

per swift 4, you can simply use textView.text.last

answered Jan 21 '19 at 07:20

Raditya Kurnianto

734
1
16
42

Obviously the question doesn’t seems talking about your case. – Raditya Kurnianto Jun 13 '20 at 15:07

How do I get the last n characters typed in a UITextView?

3 Answers3

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