NSDataAdditions.m

#import "NSDataAdditions.h"

@implementation NSData (NSDataAdditions)

+ (NSData *)base64DataFromString: (NSString *)string {
    unsigned long ixtext, lentext;
    unsigned char ch, input[4], output[3];
    short i, ixinput;
    Boolean flignore, flendtext = false;
    const char *temporary;
    NSMutableData *result;
    
    if (!string) {
        return [NSData data];
    }
    
    ixtext = 0;
    
    temporary = [string UTF8String];
    
    lentext = [string length];
    
    result = [NSMutableData dataWithCapacity: lentext];
    
    ixinput = 0;
    input[0]=0;
    input[1]=0;
    input[2]=0;
    input[3]=0;
    
    while (true) {
        if (ixtext >= lentext) {
            break;
        }
        
        ch = temporary[ixtext++];
        
        flignore = false;
        
        if ((ch >= 'A') && (ch <= 'Z')) {
            ch = ch - 'A';
        } else if ((ch >= 'a') && (ch <= 'z')) {
            ch = ch - 'a' + 26;
        } else if ((ch >= '0') && (ch <= '9')) {
            ch = ch - '0' + 52;
        } else if (ch == '+') {
            ch = 62;
        } else if (ch == '=') {
            flendtext = true;
        } else if (ch == '/') {
            ch = 63;
        } else {
            flignore = true; 
        }
        
        if (!flignore) {
            short ctcharsinput = 3;
            Boolean flbreak = false;
            
            if (flendtext) {
                if (ixinput == 0) {
                    break;
                }
                
                if ((ixinput == 1) || (ixinput == 2)) {
                    ctcharsinput = 1;
                } else {
                    ctcharsinput = 2;
                }
                
                ixinput = 3;
                
                flbreak = true;
            }
            
            input[ixinput++] = ch;
            
            if (ixinput == 4) {
                ixinput = 0;
                
                output[0] = (input[0] << 2) | ((input[1] & 0x30) >> 4);
                output[1] = ((input[1] & 0x0F) << 4) | ((input[2] & 0x3C) >> 2);
                output[2] = ((input[2] & 0x03) << 6) | (input[3] & 0x3F);
                
                for (i = 0; i < ctcharsinput; i++) {
                    [result appendBytes: &output[i] length: 1];
                }
            }
            
            if (flbreak) {
                break;
            }
        }
    }
    
    return result;
}

@end