// do something here

You may have heard that NS_ENUM works without the typedef (sort of). What I mean by this is that most of the time, it all just works even if you leave off the typedef on something like this:

NS_ENUM(NSInteger, BinaryItemType)
{
    BINARY_ITEM_TYPE_CONTACT_PHOTO = 0,
    BINARY_ITEM_TYPE_SIGNATURE_DATA,
    BINARY_ITEM_TYPE_BUSINESS_CARD,
};

However, if I ran into a situation where I did something to my code base to cause it to start throwing build errors like this:

duplicate symbol _BinaryItemType in:
    /Users/abc/Library/Developer/Xcode/DerivedData/xyz-bultlvoaxhkekcflkuawzlgzhwyq/Build/Intermediates/xyz.build/Debug-iphonesimulator/xyz.build/Objects-normal/x86_64/XYZViewController.o
    /Users/abc/Library/Developer/Xcode/DerivedData/xyz-bultlvoaxhkekcflkuawzlgzhwyq/Build/Intermediates/xyz.build/Debug-iphonesimulator/xyz.build/Objects-normal/x86_64/Contact+PDF.o
ld: 15 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

And of course, I did not realize that the typedef missing was causing this error. As soon as I changed the NS_ENUM to look like this, all went well:

typedef NS_ENUM(NSInteger, BinaryItemType)
{
    BINARY_ITEM_TYPE_CONTACT_PHOTO = 0,
    BINARY_ITEM_TYPE_SIGNATURE_DATA,
    BINARY_ITEM_TYPE_BUSINESS_CARD,
};

BTW, Happy Birthday to Rosalind Chao, who so ably portrayed Keiko O’Brien in Star Trek The Next Generation and Star Trek Deep Space Nine.