Setting attributedText, NSRangeException error

问题

Trying to set my UIText view's attributed text properties via selection. Almost works. Action to set text with red font color below. This works sometimes, but often gives an error:

Terminating app due to uncaught exception 'NSRangeException', reason: 'NSMutableRLEArray objectAtIndex:effectiveRange:: Out of bounds'

This happens even while there seems to be many more characters in the text view than indicated by the selected range.

- (IBAction)setText:(id)sender {

    NSMutableAttributedString * string = [[NSMutableAttributedString alloc] initWithAttributedString:myTextView.attributedText];
    [string addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(p1,p2)];

    myTextView.attributedText = string;

}

p1 and p2 are the start and end of the selected text. They are generated with the code below, which seems to work as expected:

- (void)textViewDidChangeSelection:(UITextView *)textView {

    UITextRange *selectedRange = [myTextView selectedTextRange];

    p1 = [myTextView offsetFromPosition:myTextView.beginningOfDocument toPosition:[selectedRange start]];
    p2 = [myTextView offsetFromPosition:myTextView.beginningOfDocument toPosition:[selectedRange end]];

 }

EDIT: I fixed the problem after reading @borrrden's comment. Instead of NSMakeRange(p1,p2)] I am using NSMakeRange(p1,p2-p1)].

回答1:

You need to be careful about NSMakeRange. I've answered another question with the same answer before, but it takes a start value and a length value, not a start value and an end value as you are trying to use it.

来源：https://stackoverflow.com/questions/15653947/setting-attributedtext-nsrangeexception-error