更改NSAtributedString颜色和字体为空范围TextView

Question

I recently started investigating how NSAtributedString works. I am building something similar to rich text editor using NSAtributedString. I have a custom written CustomRichTextEditor:UITextView and I want to overwrite default attributes for NSAtributedString using this code below:

UIFont *font = [UIFont systemFontOfSize:24.0];
NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:font,NSFontAttributeName,[UIColor darkGrayColor],NSForegroundColorAttributeName,nil];
NSMutableAttributedString* attrStr = [self.richTextEditor.attributedText mutableCopy];
[attrStr setAttributes:attributes
                 range:NSMakeRange(0, self.richTextEditor.attributedText.string.length-1)

 ];
self.richTextEditor.attributedText = attrStr;

However, because my editor is empty and range is unknown, I crash with error:

How can I set the font and color for NSAtributedString correctly when the range is unknown?

Answer 1

Well, you set the ranges length like this:

self.richTextEditor.attributedText.string.length-1

which can make errors. If you make 0 - 1 to an unsigned integer it will suddenly becomes pretty big and therefore your range will be super huge.

So what you need to do is check if you have a string.length > 0 before you make your range. Executing all the code is anyway useless if your string is empty...