Re: attributedStringByTrimmingCharactersInSet: method?

FROM : Justin Anderson
DATE : Sun Jul 23 16:44:30 2006

Here's a shorter version, though it may need more checking than just 
the one if statement.

- (NSAttributedString *)attributedStringByTrimmingCharactersInSet:
(NSCharacterSet *)set
{
   NSRange frontRange, endRange, finalRange;
   NSCharacterSet invertedSet = [set invertedSet];
   
   // Find the range of the first character you want to keep
   frontRange = [[newStr string] rangeOfCharacterFromSet:set];
   // Find the range of the last character you want to keep
   endRange = [[newStr string] rangeOfCharacterFromSet:set 
options:NSBackwardsSearch];
   
   // might need more range checks than this
   if (frontRange.location == NSNotFound)
   {
       return nil;
   }
   
   finalRange = NSMakeRange(frontRange.location, NSMaxRange(endRange) - 
frontRange.location);
   
   return [self attributedSubstringFromRange:finalRange];
}

Justin Anderson

On Jul 23, 2006, at 10:16 AM, Keith Blount wrote:

> Thanks for your reply - much appreciated.
>
> I tried your idea, but the trouble with using the
> string methods directly, such as in your example, is
> that all of the formatting and attributes of the
> attributed string get stripped, which is obviously
> counter-productive.
>
> For now I have created my own NSAttributedString
> category that provides the methods I need as follows:
>
> - (NSAttributedString
> *)attributedStringByTrimmingCharactersInSet:(NSCharacterSet
> *)set
> {
>     NSMutableAttributedString *newStr = [[self
> mutableCopy] autorelease];
>     NSRange range;
>     
>     // First clear any characters from the set from the
> beginning of the string
>     range = [[newStr string]
> rangeOfCharacterFromSet:set];
>     while (range.length != 0 && range.location == 0)
>     {
>         [newStr replaceCharactersInRange:range
> withString:@""];
>         range = [[newStr string]
> rangeOfCharacterFromSet:set];
>     }
>     
>     // Then clear them from the end
>     range = [[newStr string] rangeOfCharacterFromSet:set
> options:NSBackwardsSearch];
>     while (range.length != 0 && NSMaxRange(range) ==
> [newStr length])
>     {
>         [newStr replaceCharactersInRange:range
> withString:@""];
>         range = [[newStr string] rangeOfCharacterFromSet:set
> options:NSBackwardsSearch];
>     }
>     
>     return [[[NSAttributedString alloc]
> initWithAttributedString:newStr] autorelease];
> }
>
> - (NSAttributedString
> *)attributedStringByTrimmingWhitespace
> {
>     return [self
> attributedStringByTrimmingCharactersInSet:[NSCharacterSet
> whitespaceAndNewlineCharacterSet]];
> }
>
> This seems to work fine, though if anyone thinks this
> should be done in a better or more graceful way, I
> would be grateful to hear about it.
>
> Thanks again and all the best,
> Keith