Question

I have a situation in Objective-C where a Java-style enum would be very helpful. I have a set of layer types, and each layer has its own persistence value associated with it (stored in seconds). I want to keep these layer types in an enum, since they’re too similar to make into separate classes, like so:

typedef enum {
    ExplosionLayerType,
    FireworkLayerType,
    FireLayerType,
    FireJetLayerType
} FXLayerType;

In Java, I could easily associate these two values with something like this:

public enum FXLayerType {
    Explosion(3),
    Firework(6),
    Fire(7),
    FireJet(-1);

    private int persistence;

    FXLayerType(int persistence) {
        this.persistence = persistence;
    }
}

Is there a simple way to create a sort of lightweight class like this in Objective-C, or will need to resort to more primitive methods?

EDIT:

Various people have suggested doing something like this:

typedef enum {
    ExplosionLayerType = 3,
    FireworkLayerType = 6
} FXLayerType;

This will not work for me, since I may have something like this (Java-style enum):

Explosion(3),
Firework(6),
Dust(3);

In Java, Dust and Explosion will be treated as unique values, but direct assignment with C enums will treat them as being exactly the same.

Answer 1

If you just want a primitive container for type and value, consider this approach:

typedef struct FXLayerValue {
  FXLayerType type;
  int value;
} FXLayerValue;

Then again, a class hierarchy may be worth consideration if things become complex or are better handled dynamically. Caveat: if you have a ton of objects to save and/or create, an objc type will be overkill and degrade performance.

Unfortunately, my Java-Fu isn’t good enough to know all the lang differences for enums.