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NSString category question
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NSString category question


  • Subject: NSString category question
  • From: Koen van der Drift <email@hidden>
  • Date: Wed, 5 Mar 2003 20:34:49 -0500

Hi,

I made an NSString category that removes all white spaces from a string. My
understanding is that a category is an extension of an existing class, so I
assumed I can use it as follows:

NSString* myString = [myTextView string]; // or some other initialization

[myString removeWhiteSpace];


However, this doesn't change myString, it only works if I do:

myString = [myString removeWhiteSpace];


Maybe I misunderstand something about categories, or is the way it is
supposed to work?


Here's the code in the category:

-(NSString*) removeWhiteSpace
{
NSCharacterSet *whitespaceSet;
NSMutableString *strippedString;
NSScanner *scanner;
NSString *temp;

whitespaceSet = [NSCharacterSet whitespaceAndNewlineCharacterSet];
strippedString = [[NSMutableString alloc] init];
scanner = [NSScanner scannerWithString:self];

while( [scanner scanUpToCharactersFromSet:whitespaceSet intoString:&temp] )
{
[strippedString appendString:temp];
}

return [strippedString autorelease];
}


thanks,

- Koen.
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