Singleton.

My singleton implementation.

#pragma mark Singleton stuff

static id _sharedInstance;

+ (EKCoreDataProvider *)sharedInstance
{
        static dispatch_once_t onceToken;
        dispatch_once(&onceToken, ^{
            _sharedInstance = [[EKCoreDataProvider alloc] init];
        });
        return _sharedInstance;
}

+ (id)allocWithZone:(NSZone *)zone
{
        static dispatch_once_t onceToken;
        dispatch_once(&onceToken, ^{
            _sharedInstance = nil;
            _sharedInstance = [super allocWithZone:zone];
        });
        return _sharedInstance;
}

- (id)copyWithZone:(NSZone *)zone
{
        return self;
}

+ (id)new
{
        NSException *exception = [[NSException alloc] initWithName:kEKException
                                                            reason:kEKExceptionReason
                                                          userInfo:nil];
        [exception raise];
    
        return nil;
}