gistfile1.txt

Then you can simply use the NSArray property defined on the UILabel just like any other pre-defined property as follows:

UILabel *lbl = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 150, 150)];
[lbl setArrTitlesAssociativeObj:@[]];
lbl.arrTitlesAssociativeObj = @[];

NSObject+AssociatedObject.h

//
//  NSObject+AssociatedObject.h
//  OCLearning
//
//  Created by Manish Verma on 26/07/16.
//  Copyright © 2016 Manish Verma. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSObject (AssociatedObject)

- (void)associateValue:(id)value forKey:(void*)key;
- (id)getAssociatedValueForKey:(void*)key;

@end

NSObject+AssociatedObject.m

//
//  NSObject+AssociatedObject.m
//  OCLearning
//
//  Created by Manish Verma on 26/07/16.
//  Copyright © 2016 Manish Verma. All rights reserved.
//

#import "NSObject+AssociatedObject.h"
#import <objc/runtime.h>

@implementation NSObject (AssociatedObject)

- (void)associateValue:(id)value forKey:(void*)key {
    objc_setAssociatedObject(self, &key, value, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (id)getAssociatedValueForKey:(void*)key {
    return objc_getAssociatedObject(self, &key);
}

@end

UILabel+CustomLabel.h

//
//  UILabel+CustomLabel.h
//  OCLearning
//
//  Created by Manish Verma on 26/07/16.
//  Copyright © 2016 Manish Verma. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UILabel (CustomLabel)

@property (nonatomic, retain) NSArray *arrTitlesAssociativeObj;

@end

UILabel+CustomLabel.m

//
//  UILabel+CustomLabel.m
//  OCLearning
//
//  Created by Manish Verma on 26/07/16.
//  Copyright © 2016 Manish Verma. All rights reserved.
//

#import "UILabel+CustomLabel.h"
#import "NSObject+AssociatedObject.h"

@implementation UILabel (CustomLabel)

- (void)setArrTitlesAssociativeObj:(NSArray *)arrTitlesAssociativeObj {
    [self associateValue:arrTitlesAssociativeObj forKey:@selector(arrTitlesAssociativeObj)];
}

- (NSArray*)arrTitlesAssociativeObj {
    return [self getAssociatedValueForKey:@selector(arrTitlesAssociativeObj)];
}

@end