Question

I created a custom class object Action with three enums as instance variables:

@interface Action : NSObject  <NSCopying>

@property ImageSide imageSide; //typedef enum 
@property EyeSide eyeSide; //typedef enum 
@property PointType pointType;  //typedef enum
@property int actionId;

- (id) initWithType:(int)num eyeSide:(EyeSide)eyes type:(PointType)type imageSide:(ImageSide)image;

@end

With this implementation:

@implementation Action
@synthesize imageSide;
@synthesize eyeSide;
@synthesize pointType;
@synthesize actionId;

- (id) initWithType:(int)num eyeSide:(EyeSide)eyes type:(PointType)type imageSide:(ImageSide)image {    
    // Call superclass's initializer
    self = [super init];
    if( !self ) return nil;

    actionId = num;
    imageSide = image;
    eyeSide = eyes;
    pointType = type;

    return self;
}
@end

And in my ViewController, I try to add it as a key to a NSMutableDictionary object, like this:

   Action* currentAction = [[Action alloc] initWithType:0 eyeSide:right type:eye imageSide:top];
    pointsDict = [[NSMutableDictionary alloc] initWithCapacity:20];
    [pointsDict setObject:[NSValue valueWithCGPoint:CGPointMake(touchCoordinates.x, touchCoordinates.y)] forKey:currentAction];

However, I get this error, when setObject is called:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Action copyWithZone:]: unrecognized selector sent to instance 

I went through some answers in SO related to this error, but no one seems to solve this problem, and as I am new to iOS development I’m quite puzzled by this.

Answer 1

You declare your Action class to conform to the NSCopying protocol.

So you need to implement -(id)copyWithZone:(NSZone *)zone for that class.