ios store URL images in offline mode(not connected to internet)
===

I am fetching array of images from different urls..the images are loading perfectly..but if i need to display the images in offline mode..I cant find a right way to get it.Here is my code 

    #import "ViewController.h"

    @interface ViewController ()

    @end

    @implementation ViewController

    - (void)viewDidLoad
    {
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
    NSURL *url = [NSArray arrayWithObjects:[NSURL URLWithString: 
                                            @"http://images.wikia.com/marvelmovies/images/5/5e/The-hulk-2003.jpg"],
                  [NSURL URLWithString:@"http://cdn.gottabemobile.com/wp-content/uploads/2012/06/ios62.jpg"],
                 [NSURL URLWithString:@"http://challenge.roadef.org/2012/img/google_logo.jpg"],
                  [NSURL URLWithString:@"http://addyosmani.com/blog/wp-content/uploads/2012/03/Google-doodle-of-Richard-007.jpg"],
                  [NSURL URLWithString:@"http://techcitement.com/admin/wp-content/uploads/2012/06/apple-vs-google_2.jpg"],
                  [NSURL URLWithString:@"http://www.andymangels.com/images/IronMan_9_wallpaper.jpg"],
                  [NSURL URLWithString:@"http://sequelnews.com/wp-content/uploads/2011/11/iphone_5.jpg"],Nil];
    
    
         int row = 0;
         int column = 0;
         
         for(int i = 0; i < [(NSArray*) url count]; ++i) {
             UIImage *image = [UIImage imageWithData: [NSData dataWithContentsOfURL:(NSURL*)   [(NSArray*)url objectAtIndex:i]]]; 
             
             UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
             button.frame = CGRectMake(column*100+16, row*90, 80, 80);
             [button setImage:image forState:UIControlStateNormal]; 
             
             [button addTarget:self 
                        action:@selector(buttonClicked:) 
              forControlEvents:UIControlEventTouchUpInside];
             button.tag = i; 
             [self.view addSubview:button];
             
             if (column == 2) {
                 column = 0;
                 row++;
             } else {
                 column++;
             }
         }      
       
       
    }


Guidance please...