将UIImage转换为const char *？

Question

I need to convert a UIImage into const char * because I am using protobuffer from google and structure of message accepts this type of parameter. I started with parsing the image into NSData :

UIImage *image = [UIImage imageNamed:@"sign_up_button"];
NSData *imageData =  UIImagePNGRepresentation(image);  
const char *test = (const char*)[bytesString bytes];

But when I print the result this is what i get: \\xff\\xd8\\xff\\xe0 what is wrong because the result must be a long string with encoded characters.

Answer 1

"Printing" char* aborts, when \\0 is reached. This is a possible content of image data. You cannot "print" it. You cannot handle the data as a C-string at all, because C-strings are 0-terminated. Do not use any function that expects a C-string. It will fail.

Store a length instead and handle it as "byte data".