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An enum is defined using the enum keyword, directly inside a namespace, class, or structure. All the constant names can be declared inside the curly brackets and separated by a comma. The following defines an enum for the weekdays. Above, the WeekDays enum declares members in each line separated by a comma.
An enum type is a special data type that enables for a variable to be a set of predefined constants. The variable must be equal to one of the values that have been predefined for it. Common examples include compass directions (values of NORTH, SOUTH, EAST, and WEST) and the days of the week.
If we do not explicitly assign values to enum names, the compiler by default assigns values starting from 0. For example, in the following C program, sunday gets value 0, monday gets 1, and so on.
We don't use strong for enum property in Objective-C because enums aren't objects so we can 't specify them as strong or weak.
Apple provides a macro to help provide better code compatibility, including Swift. Using the macro looks like this.
typedef NS_ENUM(NSInteger, PlayerStateType) {
PlayerStateOff,
PlayerStatePlaying,
PlayerStatePaused
};
Documented here
Your typedef needs to be in the header file (or some other file that's #imported into your header), because otherwise the compiler won't know what size to make the PlayerState ivar. Other than that, it looks ok to me.
In the .h:
typedef enum {
PlayerStateOff,
PlayerStatePlaying,
PlayerStatePaused
} PlayerState;
With current projects you may want to use the NS_ENUM() or NS_OPTIONS() macros.
typedef NS_ENUM(NSUInteger, PlayerState) {
PLAYER_OFF,
PLAYER_PLAYING,
PLAYER_PAUSED
};
This is how Apple does it for classes like NSString:
In the header file:
enum {
PlayerStateOff,
PlayerStatePlaying,
PlayerStatePaused
};
typedef NSInteger PlayerState;
Refer to Coding Guidelines at http://developer.apple.com/
I recommend using NS_OPTIONS or NS_ENUM. You can read more about it here: http://nshipster.com/ns_enum-ns_options/
Here's an example from my own code using NS_OPTIONS, I have an utility that sets a sublayer (CALayer) on a UIView's layer to create a border.
The h. file:
typedef NS_OPTIONS(NSUInteger, BSTCMBorder) {
BSTCMBOrderNoBorder = 0,
BSTCMBorderTop = 1 << 0,
BSTCMBorderRight = 1 << 1,
BSTCMBorderBottom = 1 << 2,
BSTCMBOrderLeft = 1 << 3
};
@interface BSTCMBorderUtility : NSObject
+ (void)setBorderOnView:(UIView *)view
border:(BSTCMBorder)border
width:(CGFloat)width
color:(UIColor *)color;
@end
The .m file:
@implementation BSTCMBorderUtility
+ (void)setBorderOnView:(UIView *)view
border:(BSTCMBorder)border
width:(CGFloat)width
color:(UIColor *)color
{
// Make a left border on the view
if (border & BSTCMBOrderLeft) {
}
// Make a right border on the view
if (border & BSTCMBorderRight) {
}
// Etc
}
@end
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