Cocoa - Trim all leading whitespace from NSString

Question

(have searched, but not been able to find a simple solution to this one either here, or in Cocoa docs)

Q. How can I trim all leading whitespace only from an NSString? (i.e. leaving any other whitespace intact.)

Unfortunately, for my purposes, NSString's stringByTrimmingCharactersInSet method works on both leading and trailing.

Mac OS X 10.4 compatibility needed, manual GC.

Answer 1

This creates an NSString category to do what you need. With this, you can call NSString *newString = [mystring stringByTrimmingLeadingWhitespace]; to get a copy minus leading whitespace. (Code is untested, may require some minor debugging.)

@interface NSString (trimLeadingWhitespace) -(NSString*)stringByTrimmingLeadingWhitespace; @end  @implementation NSString (trimLeadingWhitespace) -(NSString*)stringByTrimmingLeadingWhitespace {     NSInteger i = 0;      while ((i < [self length])            && [[NSCharacterSet whitespaceCharacterSet] characterIsMember:[self characterAtIndex:i]]) {         i++;     }     return [self substringFromIndex:i]; } @end 

Answer 2

This is another solution using Regular Expressions (requires iOS 3.2):

NSRange range = [string rangeOfString:@"^\\s*" options:NSRegularExpressionSearch]; NSString *result = [string stringByReplacingCharactersInRange:range withString:@""]; 

And if you want to trim the trailing whitespaces only you can use @"\\s*$" instead.

Answer 3

This code is taking blanks.

NSString *trimmedText = [strResult stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

NSLog(@"%@",trimmedText);

Answer 4

Here is a very efficient (uses CoreFoundation) way of doing it (Taken from kissxml):

- (NSString *)trimWhitespace {
    NSMutableString *mStr = [self mutableCopy];
    CFStringTrimWhitespace((CFMutableStringRef)mStr);

    NSString *result = [mStr copy];

    [mStr release];
    return [result autorelease];
}