Limit the number of lines for UITextview

Question

I was wondering how to limit the amount of LINES (not characters as asked in other questions) a user can enter when editing a UITextField.

Ideally, I would like to limit the input to max. 10 lines.

Where would I need to start? Do I do this with a method? In

 - (BOOL)textViewShouldBeginEditing:(UITextView *)aTextView

Leptophyllous

You can find your answer in this post. – Sumac

possible duplicate of Limiting text in a UITextView – Interpretive

Answer 1

You have the right idea, but the wrong method. textView:shouldChangeTextInRange:replacementText: is called whenever the text is going to change; you can access the current content of the text view using its text property, and you can construct the new content from the passed range and replacement text with [textView.text stringByReplacingCharactersInRange:range withString:replacementText]. You can then count the number of lines and return YES to allow the change or NO to reject it.

Property

Or did you mean on-screen lines, rather than logical lines of text? – Property

Actually, yes, I want to know on-screen lines. I want to load a txt file into a UITextView and limit the lines shown on the screen to 10 or 15 and then have the rest on the next screen. It's really like a little word processor which has individual pages. That's why I want to limit the lines (on screen) displayed in the UITextView. But perhaps there is an easier way to do this? Perhaps use UIWebView? – Leptophyllous

If all you want is paged behavior, note that UITextView is a subclass of UIScrollView and so has the pagingEnabled property. – Property

I don't think this works as shouldChangeTextInRange can only count the number of lines prior to the new input. Adding a line for each time the new text is "\n" doesn't work either as the user could naturally reach the end of the line. – Exoskeleton

Answer 2

Maciek Czarnik answer does not worked for me, but it got me insights what to do.

iOS 7+

Swift

textView.textContainer.maximumNumberOfLines = 10
textView.textContainer.lineBreakMode = .byTruncatingTail

ObjC

textView.textContainer.maximumNumberOfLines = 10;
textView.textContainer.lineBreakMode = NSLineBreakByTruncatingTail;

Creatine

This should be the accepted answer now, even if it is a few years late, it works! – Poultry

This is buggy. It allows you to hit return past the end of the text view and then your cursor disappears and you have to hit delete to find it again. – Source

Swift 2: textView.textContainer.lineBreakMode = .ByTruncatingTail – Aphotic

Answer 3

Maybe this can help (iOS 7+):

textView.textContainer.maximumNumberOfLines = 10;
[textView.layoutManager textContainerChangedGeometry:textView.textContainer];

Even first line should do the trick I guess, but doesn't... Maybe its a bug in SDK

Vicarial

Answer 4

in Swift 3.0 version:

self.textView.textContainer.maximumNumberOfLines = self.textViewNumberOflines
self.textView.textContainer.lineBreakMode = .byTruncatingTail

Moulding

Answer 5

Maciek Czarnik's answer does not seem to work for me, even in iOS7. It gives me strange behavior, I don't know why.

What I do to limit the number of lines in the UITextView is simply :

(tested only in iOS7) In the following UITextViewDelegate method :

- (void)textViewDidChange:(UITextView *)textView
{
    NSUInteger maxNumberOfLines = 5;
    NSUInteger numLines = textView.contentSize.height/textView.font.lineHeight;
    if (numLines > maxNumberOfLines)
    {
        textView.text = [textView.text substringToIndex:textView.text.length - 1];
    }
}

Heel

CGSize size = [textView sizeThatFits:CGSizeMake(textView.width, MAXFLOAT)]; for me I had to calc the new height it will be for this to work – Boynton

nice solution easy and perfect – Betel

Answer 6

Here's a improved Version of Numereyes answer in Swift 4.2 / Swift 5

I made a little extension so I can reuse the code. I'm using a While-Loop to check if the size fits. This also works when the user pastes a lot of text at once.

extension UITextView {        
    var numberOfCurrentlyDisplayedLines: Int {
        let size = systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
        //for Swift <=4.0, replace with next line:
        //let size = systemLayoutSizeFitting(UILayoutFittingCompressedSize)

        return Int(((size.height - layoutMargins.top - layoutMargins.bottom) / font!.lineHeight))
    }

    /// Removes last characters until the given max. number of lines is reached
    func removeTextUntilSatisfying(maxNumberOfLines: Int) {
        while numberOfCurrentlyDisplayedLines > (maxNumberOfLines) {
            text = String(text.dropLast())
            layoutIfNeeded()
        }
    }
}

// Use it in UITextView's delegate method:
func textViewDidChange(_ textView: UITextView) {        
    textView.removeTextUntilSatisfying(maxNumberOfLines: 10)
}        

Zomba

This seems to rely on newlines present in the text, it doesn't work if there aren't any, always reports 0 lines even when there are multiple visible / displayed lines. – Amabelle

@Amabelle i think you wanted to comment this answer: https://mcmap.net/q/239894/-limit-the-number-of-lines-for-uitextview ? – Zomba

I can see why you're confused, let me explain better: when I tried your solution and the text contained newlines, it worked. But when the text contained no newlines yet was still visibly wrapped into multiple lines, the code you've given didn't calculate the number of visible lines, it returned zero. – Amabelle

Answer 7

Swift 4

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    let existingLines = textView.text.components(separatedBy: CharacterSet.newlines)
    let newLines = text.components(separatedBy: CharacterSet.newlines)
    let linesAfterChange = existingLines.count + newLines.count - 1
    return linesAfterChange <= textView.textContainer.maximumNumberOfLines
}

And if you want to limit characters also:

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        let existingLines = textView.text.components(separatedBy: CharacterSet.newlines)
        let newLines = text.components(separatedBy: CharacterSet.newlines)
        let linesAfterChange = existingLines.count + newLines.count - 1
        if(text == "\n") {
            return linesAfterChange <= textView.textContainer.maximumNumberOfLines
        }

        let newText = (textView.text as NSString).replacingCharacters(in: range, with: text)
        let numberOfChars = newText.count
        return numberOfChars <= 30 // 30 characters limit
    }
}

don't forget to add how many lines you want the limit to be in viewDidLoad:

txtView.textContainer.maximumNumberOfLines = 2

Gainsborough

Answer 8

The other solutions given do not solve an issue related to a last line being created at the end (an 11th line in the question's case).

Here is a working solution with Swift 4.0 & Xcode 9.0 beta (found on this blog post)

   class ViewController: UIViewController, UITextViewDelegate {

      @IBOutlet weak var textView: UITextView!

    override func viewDidLoad() {
        super.viewDidLoad()
        textView.delegate = self
        textView.textContainer.maximumNumberOfLines = 10
        textView.textContainer.lineBreakMode = .byWordWrapping
      }

    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {

        let existingLines = textView.text.components(separatedBy: CharacterSet.newlines)
        let newLines = text.components(separatedBy: CharacterSet.newlines)
        let linesAfterChange = existingLines.count + newLines.count - 1

        return linesAfterChange <= textView.textContainer.maximumNumberOfLines
    }

Nota bene: This solution does not handle the scenario where the last line is too long to display (text will be hidden on the far right side of the UITextView).

Rothstein

Answer 9

Swift 5.7, iOS 16

Inside your UIViewRepresentable wrapper for UITextView (or UITextField)

func makeUIView(context: Context) -> UITextView {

    let textView = UITextView() // ..or MyCustomUITextView()

    // ..your existing makeUIView body here..

    // Limit to N = 3 visible (displayed) lines.
    textView.textContainer.maximumNumberOfLines = 3

    // When visible line count is exceeded typing can continue,
    // but what's entered will be truncated so hidden from view.
    textView.textContainer.lineBreakMode = .byTruncatingTail

    // ..or prevent further text entry when limit is hit.
    // See https://developer.apple.com/documentation/uikit/nslinebreakmode
    //textView.textContainer.lineBreakMode = .byClipping

    // Set delegate now that other changes are made.
    textView.delegate = self

    return textView
}

Amabelle

Answer 10

Similar to other answers, but usable directly from Storyboard and without subclassing:

extension UITextView {
    @IBInspectable var maxNumberOfLines: NSInteger {
        set {
            textContainer.maximumNumberOfLines = maxNumberOfLines
        }
        get {
            return textContainer.maximumNumberOfLines
        }
    }
    @IBInspectable var lineBreakByTruncatingTail: Bool {
        set {
            if lineBreakByTruncatingTail {
                textContainer.lineBreakMode = .byTruncatingTail
            }
        }
        get {
            return textContainer.lineBreakMode == .byTruncatingTail
        }
    }
}

Hospitalization

Answer 11

Refer to APPLE documentation: Counting Lines of Text https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/TextLayout/Tasks/CountLines.html

    - (void)textViewDidChangeSelection:(UITextView *)textView{
NSLayoutManager *layoutManager = [textView layoutManager];
unsigned numberOfLines, index, numberOfGlyphs =
(unsigned)[layoutManager numberOfGlyphs];
NSRange lineRange;
for (numberOfLines = 0, index = 0; index < numberOfGlyphs; numberOfLines++){
    (void) [layoutManager lineFragmentRectForGlyphAtIndex:index
            effectiveRange:&lineRange];
    index = (unsigned)NSMaxRange(lineRange);
}
if(numberOfLines > 10){
    self.textField.text = self.lastString;
}

}

handle "\n"

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
if([text containsString:@"\n"]){
    NSLayoutManager *layoutManager = [textView layoutManager];
    unsigned numberOfLines, index, numberOfGlyphs =
            (unsigned)[layoutManager numberOfGlyphs];
    NSRange lineRange;
    for (numberOfLines = 0, index = 0; index < numberOfGlyphs; numberOfLines++){
        (void) [layoutManager lineFragmentRectForGlyphAtIndex:index
                effectiveRange:&lineRange];
        index = (unsigned)NSMaxRange(lineRange);
    }
    NSLog(@"lines = %d",numberOfLines);
    if(numberOfLines >= 10){
        return NO;
    }
}
self.lastString = textView.text;

return YES;

}

Putrescible