New CGIImage or CGImageRef from std::string using using base64 - objective-c

Question

everyone:
I've been working on this for days. Here's a little bit of background. I'm sending an image to a server using protobuf. The image is directly from the camera, so it is not a jpeg nor a png. I found code to get the data from the UIImage using the CGImage to create a CGImageRef. See the following code:
- (UIImage *)testProcessedImage:(UIImage *)processedImage
{
CGImageRef imageRef = processedImage.CGImage;
NSData *data1 = (NSData *) CFBridgingRelease(CGDataProviderCopyData(CGImageGetDataProvider(imageRef)));
Google protobuf uses C++ code to send and receive the bytes to and from the server. When I tried to get the data bytes back into NSData and alloc init a UIImage with that data the UIImage was always nil. This tells me that my NSData is not in the correct format.
At first, I thought my issue was with the C++ conversion, as shown with my previous question here. But after much frustration, I cut out everything in the middle and just created a UIImage with the CGImageRef and it worked. See the following code:
- (UIImage *)testProcessedImage:(UIImage *)processedImage
{
CGImageRef imageRef = processedImage.CGImage;
NSData *data1 = (NSData *) CFBridgingRelease(CGDataProviderCopyData(CGImageGetDataProvider(imageRef)));
// Added this line and cut out everything in the middle
UIImage *image = [UIImage imageWithCGImage:imageRef];
Following is a description of what I ultimately need to do. There are two parts. Part 1 takes a UIImage and converts it into a std::string.
take a UIImage
get the NSData from it
convert the data to unsigned char *
stuff the unsigned char * into a std::string
The string is what we would receive from the protobuf call. Part 2 takes the data from the string and converts it back into the NSData format to populate a UIImage. Following are the steps to do that:
convert the std::string to char array
convert the char array to a const char *
put the char * into NSData
return NSData
Now, with that background information and armed with the fact that populating the UIImage with a CGImageRef works, meaning that data in that format is the correct format to populate the UIImage, I'm looking for help in figuring out how to get the base64.data() into either a CFDataRef or a CGImageRef. Below is my test method:
- (UIImage *)testProcessedImage:(UIImage *)processedImage
{
CGImageRef imageRef = processedImage.CGImage;
NSData *data1 = (NSData *) CFBridgingRelease(CGDataProviderCopyData(CGImageGetDataProvider(imageRef)));
unsigned char *pixels = (unsigned char *)[data1 bytes];
unsigned long size = [data1 length];
// ***************************************************************************
// This is where we would call transmit and receive the bytes in a std::string
//
// The following line simulates that:
//
const std::string byteString(pixels, pixels + size);
//
// ***************************************************************************
// converting to base64
std::string encoded = base64_encode(reinterpret_cast<const unsigned char*>(byteString.c_str()), byteString.length());
// retrieving base64
std::string decoded = base64_decode(encoded);
// put byte array back into NSData format
NSUInteger usize = decoded.length();
const char *bytes = decoded.data();
NSData *data2 = [NSData dataWithBytes:(const void *)bytes length:sizeof(unsigned char)*usize];
NSLog(#"examine data");
// But when I try to alloc init a UIImage with the data, the image is nil
UIImage *image2 = [[UIImage alloc] initWithData:data2];
NSLog(#"examine image2");
// *********** Below is my convoluted approach at CFDataRef and CGImageRef ****************
CFDataRef dataRef = CFDataCreate( NULL, (const UInt8*) decoded.data(), decoded.length() );
NSData *myData = (__bridge NSData *)dataRef;
//CGDataProviderRef ref = CGDataProviderCreateWithCFData(dataRef);
id sublayer = (id)[UIImage imageWithCGImage:imageRef].CGImage;
UIImage *image3 = [UIImage imageWithCGImage:(__bridge CGImageRef)(sublayer)];
return image3;
}
As any casual observer can see, I need help. HELP!!! I've tried some of the other questions on SO, such as this one and this one and this one and cannot find the information I need for the solution. I admit part of my problem is that I do not understand much about images (like RGBA values and other stuff).