Question

In sample code, I have seen this:

typedef enum Ename { Bob, Mary, John} EmployeeName;

and this:

typedef enum {Bob, Mary, John} EmployeeName;

and this:

typedef enum {Bob, Mary, John};

but what compiled successfully for me was this:

enum {Bob, Mary, John};

I put that line in a .h file above the @interface line, and then when I #import that .h file into a different class’s .m file, methods there can see the enum.

So, when are the other variants needed?

If I could name the enum something like EmployeeNames, and then, when I type “EmployeeNames” followed by a “.”, it would be nice if a list pops up showing what the enum choices are.

Answer 1

In C (and hence Objective C), an enum type has to be prefixed with enum every time you use it.

enum MyEnum enumVar;

By making a typedef:

typedef MyEnum MyEnumT;

You can write the shorter:

MyEnumT enumVar;

The alternative declarations declare the enum itself and the typedef in one declaration.

// gives the enum itself a name, as well as the typedef
typedef enum Ename { Bob, Mary, John} EmployeeName;

// leaves the enum anonymous, only gives a name to the typedef
typedef enum {Bob, Mary, John} EmployeeName;

// leaves both anonymous, so Bob, Mary and John are just names for values of an anonymous type
typedef enum {Bob, Mary, John};