> Further to earlier answers, bear in mind you've got no guarantee that file
> extensions are correct, or even exist. Plus of course, you might have both
> .jpg and .jpeg. You might well be better iterating through, finding the UTI
> of each file, and working from that.
Oooh, that's kind of embarrassing. :) Yes, that's a very good point, that we
all should have realised before worrying about the details of file extension
comparison. So I'll retract my prior recommendations and instead suggest using
something like:
// Provided parameters:
//
// paths: Collection of NSStrings, the absolute paths of the items in
question.
// supportedTypes: Collection of UTIs (NSStrings) that you're looking for.
for (NSString *path in paths) {
NSURL *url = [[NSURL alloc] initFileURLWithPath:path];
NSString *uti = nil;
NSError *error = nil;
if ([url getResourceValue:&uti forKey:NSURLTypeIdentifierKey
error:&error]) {
for (NSString *supportedType in supportedTypes) {
if (UTTypeConformsTo(uti, supportedType)) {
// You have a match.
}
}
} else {
// Handle error
}
}
There's a lot of nasty enumeration there, rather than hashtables which make me
much happier, but I don't know of a better way off hand.
However, -[NSURL getResourceValue:forKey:error:] is only available in iOS 4.0
and later. So you'll have to find another route if you're targeting earlier
than that.
Also, if your paths are actually the contents of a folder (or folders), you
could use -[NSFileManager
enumeratorAtURL:includingPropertiesForKeys:options:errorHandler:], which will
handle the enumeration for you as well as possibly being faster - one of the
promised potentials of that method is that, since you tell it up front what
file properties you're interested in, it can pre-fetch and/or batch-fetch them.
Again, though, that's only available on iOS starting at version 4.0.
Addendum: See also the Uniform Type Identifiers Overview for more information
on UTIs. You'll note, for example, that I didn't just do isEqualToString: when
comparing them, and for good reason - all explained in the docs.
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