NSStringAdditions.m

#import "NSStringAdditions.h"

/* Base64 Encoding Table */
static char base64EncodingTable[64] = {
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
    'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};

@implementation NSString (NSStringAdditions)

+ (NSString *)stringByGeneratingUUID {
    CFUUIDRef UUIDReference = CFUUIDCreate(nil);
    CFStringRef temporaryUUIDString = CFUUIDCreateString(nil, UUIDReference);
    
    CFRelease(UUIDReference);
    
    return [NSMakeCollectable(temporaryUUIDString) autorelease];
}

+ (NSString *)base64StringFromData: (NSData *)data length: (int)length {
    unsigned long ixtext, lentext;
    long ctremaining;
    unsigned char input[3], output[4];
    short i, charsonline = 0, ctcopy;
    const unsigned char *raw;
    NSMutableString *result;
    
    lentext = [data length];
    
    if (lentext < 1) {
        return @"";
    }
    
    result = [NSMutableString stringWithCapacity: lentext];
    
    raw = [data bytes];
    
    ixtext = 0;
    
    while (true) {
        ctremaining = lentext - ixtext;
        
        if (ctremaining <= 0) {
            break;
        }
        
        for (i = 0; i < 3; i++) { 
            unsigned long ix = ixtext + i;
            
            if (ix < lentext) {
                input[i] = raw[ix];
            } else {
                input[i] = 0;
            }
        }
        
        output[0] = (input[0] & 0xFC) >> 2;
        output[1] = ((input[0] & 0x03) << 4) | ((input[1] & 0xF0) >> 4);
        output[2] = ((input[1] & 0x0F) << 2) | ((input[2] & 0xC0) >> 6);
        output[3] = input[2] & 0x3F;
        
        ctcopy = 4;
        
        switch (ctremaining) {
            case 1: 
                ctcopy = 2;
                break;
            case 2: 
                ctcopy = 3;
                break;
        }
        
        for (i = 0; i < ctcopy; i++) {
            [result appendString: [NSString stringWithFormat: @"%c", base64EncodingTable[output[i]]]];
        }
        
        for (i = ctcopy; i < 4; i++) {
            [result appendString: @"="];
        }
        
        ixtext += 3;
        charsonline += 4;
        
        if ((ixtext % 90) == 0) {
            [result appendString: @"\n"];
        }
        
        if (length > 0) {
            if (charsonline >= length) {
                charsonline = 0;
                
                [result appendString: @"\n"];
            }
        }
    }
    
    return result;
}

#pragma mark -

- (NSString *)unescapedString {
    NSMutableString *string = [NSMutableString stringWithString: self];
    
    [string replaceOccurrencesOfString: @"&amp;"  withString: @"&" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"&quot;" withString: @"\"" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"&#x27;" withString: @"'" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"&#x39;" withString: @"'" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"&#x92;" withString: @"'" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"&#x96;" withString: @"'" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"&gt;" withString: @">" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"&lt;" withString: @"<" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    
    return [NSString stringWithString: string];
}

- (NSString *)escapedString {
    NSMutableString *string = [NSMutableString stringWithString: self];
    
    [string replaceOccurrencesOfString: @"&"  withString: @"&amp;" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"\"" withString: @"&quot;" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"'"  withString: @"&#x27;" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @">"  withString: @"&gt;" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    [string replaceOccurrencesOfString: @"<"  withString: @"&lt;" options: NSLiteralSearch range: NSMakeRange(0, [string length])];
    
    return [NSString stringWithString: string];
}

@end