NSData to byte array (or array of integers) - iphone

Question

I am working with a webservice which gives me an image as an array of integers. I have managed to convert this array into an NSData object and then into a UIImage using the code below.
Now I am in doubt how I will convert an image into a similar array.
The array looks like this:
[255,216,255,224,0,16,74,70,73,70,0,1,1,1,0,96,0,96,0,0,255,219,0,67,0,8,6,6,7,6,5,8,7,7,7,9,9,8,10,12,...]
This is the code I use to convert the above array to a UIImage.
+ (UIImage *)imageFromBytes:(NSArray *)bytes
{
unsigned char *buffer = (unsigned char *) malloc(bytes.count);
int i = 0;
for (NSDecimalNumber *num in bytes)
buffer[i++] = num.intValue;
NSData *data = [NSData dataWithBytes:buffer length:bytes.count];
free(buffer);
return [UIImage imageWithData:data];
}
So, I need to convert a UIImage into an array of integers (a byte array).
Can anybody point me in the right direction?

Answer 1

You can get the data for an image with:
UIImage *image = [UIImage imageNamed:#"image.png"];
NSData *data = UIImagePNGRepresentation(image);
If you use a JPG you can use UIImageJPEGRepresentation.
And then, extract the array of bytes:
NSUInteger len = [data length];
Byte *byteData = (Byte*)malloc(len);
memcpy(byteData, [data bytes], len);
free(byteData)
You can use also the method (void)getBytes:(void *)buffer length:(NSUInteger)length from NSData:
[data getBytes:&byteData length:len];