How do I show Invisibles in GDB output window in Xcode 4?

I just tracked down a string equality bug due to string length mismatch. The extra character was '\r' which doesn't show up in the output window in Xcode 4 at all. If it had, I wouldn't have to spend nearly as much time as I did tracking the issue down.

Is it possible to show whitespace characters in the output window? If so, what magic incantation must I recite to enable it?

I tried Show Invisibles under the Edit开发者_C百科or menu, but that only worked for the code editors, not the output window. I'm using Xcode 4 on an iOS app.

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I can think of only one solution right now: Creating a category:

NSString+myAdditions.h

@interface NSString (myAdditions) 

- (NSString *)showInvisibles;

@end

NSString+myAdditions.m

#import "NSString+myAdditions.h"

@implementation NSString (myAdditions)

- (NSString *)showInvisibles
{
    NSString *regexToReplaceWhitespaces = @"([\\s])";   

    NSError *error = NULL;
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regexToReplaceWhitespaces
                                                                           options:NSRegularExpressionCaseInsensitive
                                                                             error:&error];

    NSString *result = [regex stringByReplacingMatchesInString:self
                                                       options:0
                                                         range:NSMakeRange(0, [self length])
                                                  withTemplate:@"␣"];

    return result;
}

@end

Usage

NSLog(@"show me the unseen: %@", [@"soo      many    whitespace in here  \t\t <- look two tabs!" showInvisibles]);

Output

soo␣␣␣␣␣␣many␣␣␣␣whitespace␣in␣here␣␣␣␣␣<-␣look␣two␣tabs!

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You could percent-escape your string. You can specify which characters to not escape in the third parameter (I included all of the common ones), the rest of which will be escaped:

NSLog(@"%@", CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)yourString, (CFStringRef)@" <>#%{}|\^~[]`;/?:@=&$", NULL, kCFStringEncodingUTF8);