Question

I’m trying to load thumb images in CGPDFDocument.
I wrote the following code in a function called main in class ReaderThumbFetch.

NSURL *thumbURL = [self thumbFileURL]; 

CGImageRef imageRef = NULL;

CGImageSourceRef loadRef = CGImageSourceCreateWithURL((CFURLRef)thumbURL, NULL);

if (loadRef != NULL) // Load the existing thumb image
{
    imageRef = CGImageSourceCreateImageAtIndex(loadRef, 0, NULL); // Load it
    
    CFRelease(loadRef); // Release CGImageSource reference
}

The implementation of thumbFileURL function is:

- (NSURL *)thumbFileURL
{
#ifdef DEBUGX
NSLog(@"%s", __FUNCTION__);
#endif

NSString *cachePath = [ReaderThumbCache thumbCachePathForGUID:request.guid]; // Thumb cache path

NSString *fileName = [NSString stringWithFormat:@"%@.png", request.thumbName]; // Thumb file name

return [NSURL fileURLWithPath:[cachePath stringByAppendingPathComponent:fileName]]; // File URL
}

But when I run it gives me the following error:

Undefined symbols for architecture i386:
"_CGImageSourceCreateWithURL", referenced from:
 -[ReaderThumbFetch main] in ReaderThumbFetch.o

Answer 1

add the framework ImageIOFramework.
In xcode it is done in the project setting tab: build phases->link binary with libs