Most efficient way to pull first non-whitespace line from NSTextView? - cocoa

Question

What is the most efficient way to pull the first non-whitespace line from an NSTextView?
For example, if the text is:
\n
\n
\n
This is the text I want \n
\n
Foo bar \n
\n
The result would be "This is the text I want".
Here is what I have:
NSString *content = self.textView.textStorage.string;
NSInteger len = [content length];
NSInteger i = 0;
// Scan past leading whitespace and newlines
while (i < len && [[NSCharacterSet whitespaceAndNewlineCharacterSet] characterIsMember:[content characterAtIndex:i]]) {
i++;
}
// Now, scan to first newline
while (i < len && ![[NSCharacterSet newlineCharacterSet] characterIsMember:[content characterAtIndex:i]]) {
i++;
}
// Grab the substring up to that newline
NSString *resultWithWhitespace = [content substringToIndex:i];
// Trim leading and trailing whitespace/newlines from the substring
NSString *result = [resultWithWhitespace stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
Is there a better, more efficient way?
I'm thinking of putting this in the -textStorageDidProcessEditing: NSTextStorageDelegate method so I can get it as the text is edited. That's why I'd like the method to be as efficient as possible.

Answer 1

Just use NSScanner which is designed for this sort of thing:
NSString* output = nil;
NSScanner* scanner = [NSScanner scannerWithString:yourString];
[scanner scanCharactersFromSet:[NSCharacterSet whitespaceAndNewlineCharacterSet] intoString:NULL];
[scanner scanUpToCharactersFromSet:[NSCharacterSet newlineCharacterSet] intoString:&output];
output = [output stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
Note that it's much faster if you can scan up to a particular character rather than a character set:
[scanner scanUpToString:#"\n" intoString:&output];