What is the correct encoding for filesystem path strings?

Question

When I take a path in an NSString and turn around and use it in a C API, for example:

CGDataProviderRef CGDataProviderCreateWithFilename(const char *filename );

What is the correct encoding for the path when flattening to a char*? UTF8? (ASCII??)

I feel like this should be either obvious, or obviously documented, but I'm having trouble thinking and/or finding the answer.

Answer 1

an example that worked for me using the above answer

NSString *path =@"/Users/ethansanford/Desktop/mutable string logic/mutable string logic/long-arrow-right.png" ;
CGDataProviderRef provider = CGDataProviderCreateWithFilename(path.fileSystemRepresentation);
imageRef2 =CGImageCreateWithPNGDataProvider(provider, NULL, false, kCGRenderingIntentDefault);

Answer 2

Use -[NSString fileSystemRepresentation].