Base64 Encoding for NSString

Question

I am trying to post the username and password to the server. I want to convert this username and password into Base64 Encoding. So this encoded string will be added for the Authorization field.

Is there any API already available to do the Base64 encoding in iOS or we have write on our own ??

Answer 1

This can be done by implementing a class method for base64 conversion the below code is for conversion..

+ (NSString*)base64forData:(NSData*)theData 
{
    const uint8_t* input = (const uint8_t*)[theData bytes];
    NSInteger length = [theData length];

    static char table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

    NSMutableData* data = [NSMutableData dataWithLength:((length + 2) / 3) * 4];
    uint8_t* output = (uint8_t*)data.mutableBytes;

    NSInteger i;
    for (i=0; i < length; i += 3) {
        NSInteger value = 0;
        NSInteger j;
        for (j = i; j < (i + 3); j++) {
            value <<= 8;

            if (j < length) {
                value |= (0xFF & input[j]);
            }
        }

        NSInteger theIndex = (i / 3) * 4;
        output[theIndex + 0] =                    table[(value >> 18) & 0x3F];
        output[theIndex + 1] =                    table[(value >> 12) & 0x3F];
        output[theIndex + 2] = (i + 1) < length ? table[(value >> 6)  & 0x3F] : '=';
        output[theIndex + 3] = (i + 2) < length ? table[(value >> 0)  & 0x3F] : '=';
    }

    return [[[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding] autorelease];
}

and in your URL request add the following code for to sent the username and password for authorization...

[request addValue:[NSString stringWithFormat:@"Basic %@",[className base64forData:[[NSString stringWithFormat:@"%@:%@",UsernameString,passwordString] dataUsingEncoding: NSUTF8StringEncoding]]] forHTTPHeaderField:@"Authorization"];