Why can I not use my constant in the switch - case statement in Objective-C ? [error = Expression is not an integer constant expression]

Question

So I have an issue with using a constant variable in the following switch statement in Objective-C.

I have Constants.h with the following:

Answer 1

I would normally follow what Apple seem to do and define a typedef enum in the .h file like this.

typedef NS_ENUM(NSInteger, PSOption) {
  PSOption1,
  PSOption2,
  PSOption3,
  PSOption4,
};  

You can then use it in your case statement and even pass it into functions as well as a type e.g.

- (void)myMethod:(PSOption)option;

A further advantage of doing this over a #define is code completion and compiler checking