Create UITextRange from NSRange

Solution 1:

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];
}

Solution 2:

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;

Solution 3:

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
    }
}

Solution 4:

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
    }
}