Detect moment when newline starts in UITextView - ios

Question

I try to detect when carriage goes at new line in UITextView. I can detect it by comparison total later width with UITextView width:
CGSize size = [textView.text sizeWithAttributes:textView.typingAttributes];
if(size.width > textView.bounds.size.width)
NSLog (#"New line");
But it dose not work proper way because -sizeWithAttributes:textView returns only width of letters without indentation width. Help please solve this.

Answer 1

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.

Answer 2

answer of #n00bProgrammer in Swift-4 with more precise line break detection.
#n00bProgrammer answer is perfect except one thing it reacts differently when the user starts typing in a first line, it presents that Started New Line too.
Overcoming issue, here is the refined code
var previousRect = CGRect.zero
func textViewDidChange(_ textView: UITextView) {
let pos = textView.endOfDocument
let currentRect = textView.caretRect(for: pos)
self.previousRect = self.previousRect.origin.y == 0.0 ? currentRect : self.previousRect
if currentRect.origin.y > self.previousRect.origin.y {
//new line reached, write your code
print("Started New Line")
}
self.previousRect = currentRect
}

Answer 3

For Swift use this
previousRect = CGRectZero
func textViewDidChange(textView: UITextView) {
var pos = textView.endOfDocument
var currentRect = textView.caretRectForPosition(pos)
if(currentRect.origin.y > previousRect?.origin.y){
//new line reached, write your code
}
previousRect = currentRect
}

Answer 4

You can use the UITextViewDelegate
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText: (NSString *)text
{
BOOL newLine = [text isEqualToString:#"\n"];
if(newLine)
{
NSLog(#"User started a new line");
}
return YES;
}

Answer 5

Swift 3
The accepted answer and the swift version works fine, but here is a Swift 3 version for the lazy people out there.
class CustomViewController: UIViewController, UITextViewDelegate {
let textView = UITextView(frame: .zero)
var previousRect = CGRect.zero
override func viewDidLoad(){
textView.frame = CGRect(
x: 20,
y: 0,
width: view.frame.width,
height: 50
)
textView.delegate = self
view.addSubview(textView)
}
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 {
print("new line")
}
}
previousRect = currentRect
}
}

Answer 6

SWIFT 4
If you don't want to use previousRect. Let's try this:
func textViewDidChange(_ textView: UITextView) {
let pos = textView.endOfDocument
let currentRect = textView.caretRect(for: pos)
if (currentRect.origin.y == -1 || currentRect.origin.y == CGFloat.infinity){
print("Yeah!, I've gone to a new line")
//-1 for new line with a char, infinity is new line with a space
}
}

Answer 7

SWIFT 5
Lets not overcomplicate things.
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
if text == "\n" {
// return pressed
}
}

Answer 8

You need to get the height of the text, not the width. Use either sizeWithFont:constrainedToSize:lineBreakMode: (if you need to support iOS 6 or earlier) or use boundingRectWithSize:options:attributes:context: if you only support iOS 7.