Detect Moment When Newline Starts in Uitextview

Detect moment when newline starts in UITextView

This is how I would do it:

• Get the UITextPosition of the last character.
• Call caretRectForPosition on your UITextView.
• Create a CGRect variable and initially store CGRectZero in it.
• In your textViewDidChange: method, call caretRectForPosition: by passing the UITextPosition.
• Compare it with the current value stored in the CGRect variable. If the new y-origin of the caretRect is greater than the last one, it means a new line has been reached.

Sample code:

CGRect previousRect = CGRectZero;
- (void)textViewDidChange:(UITextView *)textView{

    UITextPosition* pos = yourTextView.endOfDocument;//explore others like beginningOfDocument if you want to customize the behaviour
    CGRect currentRect = [yourTextView caretRectForPosition:pos];

    if (currentRect.origin.y > previousRect.origin.y){
            //new line reached, write your code
        }
    previousRect = currentRect;

}

Also, you should read the documentation for UITextInput protocol reference here. It is magical, I'm telling you.

Let me know if you have any other issues with this.

UITextView (editing) - detecting that next line event occured

Will detect line changes from anything to hitting "return", backspacing to reduce line-count, typing till the end of the line and a word-wrap occurs, etc. (*Note: MUST adjust variables for font size, I recommend not using hard coded numbers like in my example below).

previousNumberOfLines = ((hiddenText.contentSize.height-37+21)/(21));//numbers will change according to font size
NSLog(@"%i", previousNumberOfLines);

Detect new-line character for auto enter new line text on UITextView on iOS

The UITextView doesn't automatically enter a newline character once its text reaches the end of the line -- it simply wraps around with a line break. But if you want a string representation of the UITextView text which includes newline characters to indicate the various line breaks, try this:

// This method takes in the `UITextView` and returns the string
// representation which includes the newline characters
- (NSString*)textViewWithNewLines:(UITextView*)textView {

    // Create a variable to store the new string
    NSString *stringWithNewlines = @"";

    // Get the height of line one and store it in
    // a variable representing the height of the current
    // line
    int currentLineHeight = textView.font.lineHeight;

    // Go through the text view character by character
    for (int i = 0 ; i < textView.text.length ; i ++) {

        // Place the cursor at the current character
        textView.selectedRange = NSMakeRange(i, 0);

        // And use the cursor position to help calculate
        // the current line height within the text view
        CGPoint cursorPosition = [textView caretRectForPosition:textView.selectedTextRange.start].origin;

        // If the y value of the cursor is greater than
        // the currentLineHeight, we've moved onto the next line
        if (cursorPosition.y > currentLineHeight) {

            // Increment the currentLineHeight such that it's
            // set to the height of the next line
            currentLineHeight += textView.font.lineHeight;

            // If there isn't a user inputted newline already,
            // add a newline character to reflect the new line.
            if (textView.text.length > i - 1 &&
                [textView.text characterAtIndex:i-1] != '\n') {
                stringWithNewlines = [stringWithNewlines stringByAppendingString:@"\n"];
            }

            // Then add the character to the stringWithNewlines variable
            stringWithNewlines = [stringWithNewlines stringByAppendingString:[textView.text substringWithRange:NSMakeRange(i, 1)]];
        } else {

            // If the character is still on the "current line" simply
            // add the character to the stringWithNewlines variable
            stringWithNewlines = [stringWithNewlines stringByAppendingString:[textView.text substringWithRange:NSMakeRange(i, 1)]];
        }
    }

    // Return the string representation of the text view
    // now containing the newlines
    return stringWithNewlines;
}

Swift 3 - Detecting new lines in UITextView

I solved the problem by myself, I will post the code below if someone need it (check comments in the code):

func textViewDidChange(_ textView: UITextView) {
    let pos = textView.endOfDocument
    let currentRect = textView.caretRect(for: pos)
    if previousRect != CGRect.zero {
        if currentRect.origin.y > previousRect.origin.y {
            // Array of Strings
            var currentLines = textView.text.components(separatedBy: "\n")
            // Remove Blank Strings
            currentLines = currentLines.filter{ $0 != "" }
            //increase the counter counting how many items inside the array
            counter = currentLines.count
        }
    }
    previousRect = currentRect
}

UITextView/NSAttribute: Detect if word starts with a particular symbol

Assuming you keep # or @ in the text, you can modify the answer in Larme's comment:

let regex = try! NSRegularExpression(pattern: "(?:#|@)\\w+", options: [])

func textViewDidChange(_ textView: UITextView) {
    let attrStr = NSMutableAttributedString(attributedString: textView.attributedText ?? NSAttributedString())
    let plainStr = attrStr.string
    attrStr.addAttribute(.foregroundColor, value: UIColor.black, range: NSRange(0..<plainStr.utf16.count))

    let matches = regex.matches(in: plainStr, range: NSRange(0..<plainStr.utf16.count))

    for match in matches {
        let nsRange = match.range
        let matchStr = plainStr[Range(nsRange, in: plainStr)!]
        let color: UIColor
        if matchStr.hasPrefix("#") {
            color = .red
        } else {
            color = .blue
        }
        attrStr.addAttribute(.foregroundColor, value: color, range: nsRange)
    }

    textView.attributedText = attrStr
}

I just have changed the pattern, adapted to Swift 4.1, fixed some bugs, removed some redundant codes and added some code to change colors.

Obj-C- Detecting textView line break?

Im not sure if this is gonna help at all since im also fairly new to obj-c but give it a go

-(void)textViewDidChange:(UITextView *)textView
  {
    CGFloat fixedWidth = textView.frame.size.width;
    CGSize newSize = [textView sizeThatFits:CGSizeMake(fixedWidth, MAXFLOAT)];
    CGRect newFrame = textView.frame;
    newFrame.size = CGSizeMake(fmaxf(newSize.width, fixedWidth), 
    newSize.height);
    textView.frame = newFrame;
 }

Make sure you also disable scrolling

   textview.scrollEnabled = NO;

Detect when a line break has been erased inside a UITextView - Objective C

Implement the delegate

-(BOOL)textView:shouldChangeTextInRange:replacementText:

If a delete occurs, you will have replacementText with length 0, and you can look at the textView.text at range to see what was deleted:

[textView.text substringWithRange:range]

Replace all line breaks with a space in a UITextView

You can use UITextViewDelegate's textViewDidChange(_:) method to listen whenever the text view's text changes. Inside here, you can then replace all occurrences of a newline (\n) with an empty String ("").

class ViewController: UIViewController {
    @IBOutlet weak var textView: UITextView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        textView.delegate = self
    }
}

extension ViewController: UITextViewDelegate {
    func textViewDidChange(_ textView: UITextView) {
        let text = textView.text.replacingOccurrences(of: "\n", with: "")
        textView.text = text
    }
}

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