Is it possible to scope enums to a class in Objective-C? - objective-c

Question

I'm new to Objective-C and trying to figure out enums. Is there a way to scope an enum to a class so that the values could be used by another class? Something like this:
#interface ClassA {
typedef enum {
ACCEPTED,
REJECTED
} ClassAStatus;
}
#end
#interface ClassB {
typedef enum {
ACCEPTED,
REJECTED
} ClassBStatus;
}
#end
Though that does not work, obviously. Or is there a better way to do enums altogether?
Edit: I guess my wording wasn't clear, but I'm not asking how to declare enums. I'm aware that putting them at the top of the file works. I'm asking if there's a way to scope them so the values aren't global to the entire file.

Answer 1

You have to prefix your public enums. Simply put the enum definition in the header of your class.
// ClassA.h
typedef enum {
ClassAStatusAccepted,
ClassAStatusRejected
} ClassAStatus;
#interface ClassA {
ClassAStatus status;
}
#end
// ClassB.h
typedef enum {
ClassBStatusAccepted,
ClassBStatusRejected
} ClassBStatus;
#interface ClassB {
ClassBStatus status;
}
#end
This is how Apple does it.
Or you could use the new style:
// UIView.h
typedef NS_ENUM(NSInteger, UIViewAnimationCurve) {
UIViewAnimationCurveEaseInOut, // slow at beginning and end
UIViewAnimationCurveEaseIn, // slow at beginning
UIViewAnimationCurveEaseOut, // slow at end
UIViewAnimationCurveLinear
};

Answer 2

Just put the enum right at the top of your .h, like Apple does in UITableView.h, for example:
//
// UITableView.h
// UIKit
//
// Copyright (c) 2005-2012, Apple Inc. All rights reserved.
//
#import <Foundation/Foundation.h>
#import <CoreGraphics/CoreGraphics.h>
#import <UIKit/UIScrollView.h>
#import <UIKit/UISwipeGestureRecognizer.h>
#import <UIKit/UITableViewCell.h>
#import <UIKit/UIKitDefines.h>
typedef NS_ENUM(NSInteger, UITableViewStyle) {
UITableViewStylePlain, // regular table view
UITableViewStyleGrouped // preferences style table view
};
typedef NS_ENUM(NSInteger, UITableViewScrollPosition) {
UITableViewScrollPositionNone,
UITableViewScrollPositionTop,
UITableViewScrollPositionMiddle,
UITableViewScrollPositionBottom
}; // scroll so row of interest is completely visible at top/center/bottom of view
typedef NS_ENUM(NSInteger, UITableViewRowAnimation) {
UITableViewRowAnimationFade,
UITableViewRowAnimationRight, // slide in from right (or out to right)
UITableViewRowAnimationLeft,
UITableViewRowAnimationTop,
UITableViewRowAnimationBottom,
UITableViewRowAnimationNone, // available in iOS 3.0
UITableViewRowAnimationMiddle, // available in iOS 3.2. attempts to keep cell centered in the space it will/did occupy
UITableViewRowAnimationAutomatic = 100 // available in iOS 5.0. chooses an appropriate animation style for you
};
You probably recognize some of these name, but you may not have been aware they were actually apart of a public enum in Apple's header files.

Answer 3

Just want to add to #DrummerB's answer that I usually write like this. The namespace in camelCase, and then the constant in upper case.
typedef enum {
ClassAStatus_ACCEPTED,
ClassAStatus_REJECTED
} ClassAStatus;