UIImagePIckerController所选图像为Base64字符串

Question

我正在尝试从iOS UIImagePickerController所选事件中检索Base64字符串，如下所示。

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    //on selected

    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];

    NSData *imgData = UIImageJPEGRepresentation(image, 1.0);

    NSString *imageString = [[NSString alloc] initWithBytes: [imgData bytes] length:[imgData length] encoding:NSUTF8StringEncoding];

    //NSLog(@"Image Data: %@", imageString); it returns Nothing except "Image Data: "

    [picker dismissModalViewControllerAnimated:YES];
    [picker.view removeFromSuperview];
    [picker release];
}

Answer 1

+ (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];
}