Create UITextRange from NSRange

I need to find the pixel-frame for different ranges in a textview. I'm using the - (CGRect)firstRectForRange:(UITextRange *)range; to do it. However I can't find out how to actually create a UITextRange.

Basically this is what I'm looking for:

- (CGRect)frameOfTextRange:(NSRange)range inTextView:(UITextView *)textView {

    UITextRange*range2 = [UITextRange rangeWithNSRange:range]; //DOES NOT EXIST 
    CGRect rect = [textView firstRectForRange:range2];
    return rect;
}

Apple says one has to subclass UITextRange and UITextPosition in order to adopt the UITextInput protocol. I don't do that, but I tried anyway, following the doc's example code and passing the subclass to firstRectForRange which resulted in crashing.

If there is a easier way of adding different colored UILables to a textview, please tell me. I have tried using UIWebView with content editable set to TRUE, but I'm not fond of communicating with JS, and coloring is the only thing I need.

Thanks in advance.

You can create a text range with the method textRangeFromPosition:toPosition. This method requires two positions, so you need to compute the positions for the start and the end of your range. That is done with the method positionFromPosition:offset, which returns a position from another position and a character offset.

- (CGRect)frameOfTextRange:(NSRange)range inTextView:(UITextView *)textView
{
    UITextPosition *beginning = textView.beginningOfDocument;
    UITextPosition *start = [textView positionFromPosition:beginning offset:range.location];
    UITextPosition *end = [textView positionFromPosition:start offset:range.length];
    UITextRange *textRange = [textView textRangeFromPosition:start toPosition:end];
    CGRect rect = [textView firstRectForRange:textRange];
    return [textView convertRect:rect fromView:textView.textInputView];
}

It is a bit ridiculous that seems to be so complicated. A simple "workaround" would be to select the range (accepts NSRange) and then read the selectedTextRange (returns UITextRange):

- (CGRect)frameOfTextRange:(NSRange)range inTextView:(UITextView *)textView {
    textView.selectedRange = range;
    UITextRange *textRange = [textView selectedTextRange]; 
    CGRect rect = [textView firstRectForRange:textRange];
    return rect;
}

This worked for me even if the textView is not first responder.

---

If you don't want the selection to persist, you can either reset the selectedRange:

textView.selectedRange = NSMakeRange(0, 0);

...or save the current selection and restore it afterwards

NSRange oldRange = textView.selectedRange;
// do something
// then check if the range is still valid and
textView.selectedRange = oldRange;

Swift 4 of Andrew Schreiber's answer for easy copy/paste

extension NSRange {
    func toTextRange(textInput:UITextInput) -> UITextRange? {
        if let rangeStart = textInput.position(from: textInput.beginningOfDocument, offset: location),
            let rangeEnd = textInput.position(from: rangeStart, offset: length) {
            return textInput.textRange(from: rangeStart, to: rangeEnd)
        }
        return nil
    }
}

To the title question, here is a Swift 2 extension that creates a UITextRange from an NSRange.

The only initializer for UITextRange is a instance method on the UITextInput protocol, thus the extension also requires you pass in UITextInput such as UITextField or UITextView.

extension NSRange {
    func toTextRange(textInput textInput:UITextInput) -> UITextRange? {
        if let rangeStart = textInput.positionFromPosition(textInput.beginningOfDocument, offset: location),
            rangeEnd = textInput.positionFromPosition(rangeStart, offset: length) {
            return textInput.textRangeFromPosition(rangeStart, toPosition: rangeEnd)
        }
        return nil
    }
}

Swift 4 of Nicolas Bachschmidt's answer as an UITextView extension using swifty Range<String.Index> instead of NSRange:

extension UITextView {
    func frame(ofTextRange range: Range<String.Index>?) -> CGRect? {
        guard let range = range else { return nil }
        let length = range.upperBound.encodedOffset-range.lowerBound.encodedOffset
        guard
            let start = position(from: beginningOfDocument, offset: range.lowerBound.encodedOffset),
            let end = position(from: start, offset: length),
            let txtRange = textRange(from: start, to: end)
            else { return nil }
        let rect = self.firstRect(for: txtRange)
        return self.convert(rect, to: textInputView)
    }
}

Possible use:

guard let rect = textView.frame(ofTextRange: text.range(of: "awesome")) else { return }
let awesomeView = UIView()
awesomeView.frame = rect.insetBy(dx: -3.0, dy: 0)
awesomeView.layer.borderColor = UIColor.black.cgColor
awesomeView.layer.borderWidth = 1.0
awesomeView.layer.cornerRadius = 3
self.view.insertSubview(awesomeView, belowSubview: textView)

Here is explain.

> A UITextRange object represents a range of characters in a text > container; in other words, it identifies a starting index and an > ending index in string backing a text-entry object. > > Classes that adopt the UITextInput protocol must create custom > UITextRange objects for representing ranges within the text managed by > the class. The starting and ending indexes of the range are > represented by UITextPosition objects. The text system uses both > UITextRange and UITextPosition objects for communicating text-layout > information. There are two reasons for using objects for text ranges > rather than primitive types such as NSRange: > > Some documents contain nested elements (for example, HTML tags and > embedded objects) and you need to track both absolute position and > position in the visible text. > > The WebKit framework, which the iPhone text system is based on, > requires that text indexes and offsets be represented by objects. > > If you adopt the UITextInput protocol, you must create a custom > UITextRange subclass as well as a custom UITextPosition subclass.

For example like in those sources