In my C code I generally have an enum case called count at the end. But when I use my enum in Swift it will also have that value, which I must handle in switch statements.
Is there some attribute I can use to exclude a case when importing into Swift?
You can use the NS_SWIFT_UNAVAILABLE macro on enumerators:
typedef NS_ENUM(unsigned, Foo) {
bar,
baz,
count NS_SWIFT_UNAVAILABLE("Count does not represent a case")
};
NS_SWIFT_UNAVAILABLE, like any __attribute__ that you want to apply to an enumerator, goes after the enumerator name but before the = if you need one.
The macro is defined if you include <Foundation/Foundation.h>. If you include CoreFoundation, you get CF_SWIFT_UNAVAILABLE, which does the same thing. If you include neither, you can use the long form:
__attribute__((availability(swift, unavailable, message="your message")))
Enumerators that are annotated with NS_SWIFT_UNAVAILABLE won't show up in autocomplete, and won't cause build issues if they're not handled on the Swift side. If you attempt to use it, you get a hard error that includes your message.
Keep in mind that starting with Swift 5, you may need to use NS_CLOSED_ENUM instead of NS_ENUM if your purpose is to avoid having a default case.