Adding Favorites Feature to IOS App

[learningtocode]

I am new to Objective-C and am trying to develop a simple app for kids. I have looked all over this forum, and across the internet, and I havent quite gotten this answer. What I am trying to do is create an application that has 2 different arrays that link to various UIImages (over 200). I would like to set up a Favorites button, so that when selecting it on that specific image, it saves to a Favorites tab. Whats the best way of going about this. So far I have a tab view linked to a navigation view that is linked up to a Table View that goes to the image. Thanks

[Domele]

I'd create a FavoriteImage object. Give it one property, a UIImage named image. Also, make it comply to the NSCoding protocol. Here is a tutorial on how to make it comply to NSCoding: How To Save Your App Data With NSCoding and NSFileManager | Ray Wenderlich You can ignore the stuff about NSFileManager.

Then, I'd create a singleton (Duncan C shows how to make a singleton here: http://www.iphonedevsdk.com/forum/ip...singleton.html) and give it 3 methods and a NSMutableArray property named internal_favoriteImages:

- (void)addFavoriteImage:(FavoriteImage *)favoriteImage;
- (void)removeFavoriteImage:(FavoriteImage *)favoriteImage;
- (NSArray *)favoriteImages;

In addFavoriteImage, add the passed in image to your internal_favoriteImages array. Then, wrap your array into a NSData object using NSKeyedArchiver's archivedDataWithRootObject: class method. For this to work, your FavoriteImage object needs to comply to NSCoding. Then save the NSData object to NSUserDefaults.

In removeFavoriteImage, do the same thing as you did in addFavoriteImage except remove the passed in image from the array.

In favoriteImages, create a non mutable version of the array using NSArray's arrayWithArray: method and return that.

In your Singleton init method, check if a NSData object has been saved into NSUserDefaults and if so, retrieve the NSData object. Unpack it using NSKeyedUnarchiver's unarchiveObjectWithData: class method. If there is no NSData object present, just initialize your internal_FavoriteImages array.

The only problem with this approach is you are going to be saving the image data again which causes loss of disk space. I'm too lazy at the moment to figure out a solution to that so I'll let someone else tackle that problem.

[X-RaY]

I guess all the images are stored somewhere, right?
make sure the name of the images has some id in it.
Then, when someone favorites an image, store the id in an array, set a variable to let the favoritestab know it has to refresh.
In the refresh, just iterate through the array and display the corresponding image.
then, when the favorite is un-favorited, remove the id from the array and refresh the tab again

when the app is pushed to the background, store the array in the nsuserdefaults.
easiest way imo, and you won't have to save a duplicate of the favorite images.

[Domele]

I agree with the ID part but if you have to set a variable for the favorite images controller to refresh, that's going to make it dependent on another class. That's not a good thing. By the way, if you use the ID, you won't need to make a separate FavoriteImage class. But I still advise that you make the singleton.

[learningtocode]

Thank you guys for both your inputs. I will give it a shot!!!