enum Values to NSString (iOS)

Solution 1:

I didn't like putting the enum on the heap, without providing a heap function for translation. Here's what I came up with:

typedef enum {value1, value2, value3} myValue;
#define myValueString(enum) [@[@"value1",@"value2",@"value3"] objectAtIndex:enum]

This keeps the enum and string declarations close together for easy updating when needed.

Now, anywhere in the code, you can use the enum/macro like this:

myValue aVal = value2;
NSLog(@"The enum value is '%@'.", myValueString(aVal));

outputs: The enum value is 'value2'.

To guarantee the element indexes, you can always explicitly declare the start(or all) enum values.

enum {value1=0, value2=1, value3=2};

Solution 2:

This is answered here: a few suggestions on implementation

The bottom line is Objective-C is using a regular, old C enum, which is just a glorified set of integers.

Given an enum like this:

typedef enum { a, b, c } FirstThreeAlpha;

Your method would look like this:

- (NSString*) convertToString:(FirstThreeAlpha) whichAlpha {
    NSString *result = nil;

    switch(whichAlpha) {
        case a:
            result = @"a";
            break;
        case b:
            result = @"b";
            break;
        case c:
            result = @"c";
            break;

        default:
            result = @"unknown";
    }

    return result;
}

Solution 3:

I will introduce is the way I use, and it looks better than previous answer.(I thinks)

I would like to illustrate with UIImageOrientation for easy understanding.

typedef enum {
    UIImageOrientationUp = 0,            // default orientation, set to 0 so that it always starts from 0
    UIImageOrientationDown,          // 180 deg rotation
    UIImageOrientationLeft,          // 90 deg CCW
    UIImageOrientationRight,         // 90 deg CW
    UIImageOrientationUpMirrored,    // as above but image mirrored along other axis. horizontal flip
    UIImageOrientationDownMirrored,  // horizontal flip
    UIImageOrientationLeftMirrored,  // vertical flip
    UIImageOrientationRightMirrored, // vertical flip
} UIImageOrientation;

create a method like:

NSString *stringWithUIImageOrientation(UIImageOrientation input) {
    NSArray *arr = @[
    @"UIImageOrientationUp",            // default orientation
    @"UIImageOrientationDown",          // 180 deg rotation
    @"UIImageOrientationLeft",          // 90 deg CCW
    @"UIImageOrientationRight",         // 90 deg CW
    @"UIImageOrientationUpMirrored",    // as above but image mirrored along other axis. horizontal flip
    @"UIImageOrientationDownMirrored",  // horizontal flip
    @"UIImageOrientationLeftMirrored",  // vertical flip
    @"UIImageOrientationRightMirrored", // vertical flip
    ];
    return (NSString *)[arr objectAtIndex:input];
}

All you have to do is :

1. name your function.

2. copy contents of enum and paste that between NSArray *arr = @[ and ]; return (NSString *)[arr objectAtIndex:input];

3. put some @ , " , and comma

4. PROFIT!!!!

Solution 4:

This will be validated by compiler, so you won't mix up indices accidentally.

NSDictionary *stateStrings =
 @{
   @(MCSessionStateNotConnected) : @"MCSessionStateNotConnected",
   @(MCSessionStateConnecting) : @"MCSessionStateConnecting",
   @(MCSessionStateConnected) : @"MCSessionStateConnected",
  };
NSString *stateString = [stateStrings objectForKey:@(state)];

var stateStrings: [MCSessionState: String] = [
    .notConnected : "MCSessionState.notConnected",
    .connecting : "MCSessionState.connecting",
    .connected : "MCSessionState.connected"
]
var stateString = stateStrings[MCSessionState.Connected]

UPDATE: A more Swifty way is to extend the enum with CustomStringConvertible conformance. Also, this way the compiler will safeguard to implement every new addition to the underlying enum (whereas using arrays does not), as switch statements must be exhaustive.

extension MCSessionState: CustomStringConvertible {
    
    public var description: String {
        switch self {
        case .notConnected:
            return "MCSessionState.notConnected"
        case .connecting:
            return "MCSessionState.connecting"
        case .connected:
            return "MCSessionState.connected"
        @unknown default:
            return "Unknown"
        }
    }
}

// You can use it like this.
var stateString = MCSessionState.connected.description

// Or this.
var stateString = "\(MCSessionState.connected)"