Change text color in specific situation - ios

Question

I'm using this method to change color to few chars of my UITextView
+(void)changeColorToTextObject : (UITextView *)textView ToColor : (UIColor *)color FromLocation : (int)location WithLength : (int)length
{
NSMutableAttributedString *text = [[NSMutableAttributedString alloc] initWithAttributedString: textView.attributedText];
[text addAttribute:NSForegroundColorAttributeName value:color range:NSMakeRange(location, length)];
[textView setAttributedText: text];
}
It works great but after I change the specific range I want to be able to continue with the previous color and not with the new color that I just changed to.
How can I do it?

Answer 1

Actually, when working with attributed text, I found it best practice to set content first and style second (which actually originates from old typesetting rules).
In your case, I would first set the whole text on the UITextView, and then call the method changeColorToTextObject:ToColor:FromLocation:WithLength specifying only the portion of the text you want in a different color.
However, if you are not talking about static content, but rather something like a word processor app, where the user can change text color and continues to write afterwards, you need to think about how you want this app to work. Consider the following method:
- (void)highlightSelectedText {
UIColor *highlightColor = [UIColor redColor];
[self changeColorToTextObject:self.textView ToColor:highlightColor FromLocation:self.textView.selectedRange.location WithLength:self.textView.selectedRange.length];
}
This method allows you to highlight the specific part of the text, the user has currently selected:
If the user then continues typing, the new text will appear in red:
If instead, they put the focus at a place where font color is black, they will continue writing in black:
When you think about a word processor, that seems actually pretty familiar. And if that is good enough for you, you are good to go.
The only border case you need to worry about then is what you do, when there is no text selected.
However, if you need more control over the dynamic behavior of your UITextView (and if you are >iOS 7), you should consider using Text Kit, and in particular subclassing NSTextStorage. There is a introduction video to Text Kit from WWDC 2013, and a great tutorial by Ray Wenderlich.

Answer 2

Save your previous color into a 'UIColor' property before apply the attributedText to the UITextView, and assign it to the UITextView after using the 'changeColorToTextObject' method.