Allowing user to install an app via an ad in another app

I am building a third party library that is essentially an ad network, i.e., it will provide ads in apps. So, I need to allow users to install apps from within the app, using an ad - something like Facebook, where you see an app advertisement, you click that ad and install it - all within Facebook.

So I need to way to let users install those apps without leaving the app in which the ad is shown. Another recent example of this is Appsfire. They allow users to tap on ads, install those apps and return to Appsfire (essentially not letting the user leave).

I tried searching for an AppStore API but all I could find is the API to query AppStore, not a way to display an app and let users install it.

Solution

You're looking for SKStoreProductViewController - which looks like this:

enter image description here

^{It works for apps, songs, books - anything on the iTunes store. Image credit techotopia.}

This is a good tutorial on the subject - usage comes down to:

Importing the StoreKit framework,
Creating an instance of the view controller,
Assigning a delegate,
Telling it what to display,
Presenting it,
And implementing the delegate methods

Which comes down to this code:

SKStoreProductViewController *storeViewController = [[SKStoreProductViewController alloc] init];
storeViewController.delegate = self;
NSDictionary *parameters = @{SKStoreProductParameterITunesItemIdentifier:[NSNumber numberWithInteger:<item id>]};
[storeViewController loadProductWithParameters:parameters 
             completionBlock:^(BOOL result, NSError *error) {
            if (result)
                [self presentViewController:storeViewController
                                   animated:YES
                                 completion:nil];
}];

You can get your iTunes product ID using iTunes' LinkMaker. The ID is also shown under the Manage your Apps section of iTunes Connect:

enter image description here

The one required delegate method is a simple dismissal action:

- (void)productViewControllerDidFinish:(SKStoreProductViewController *)viewController
{
    [viewController dismissViewControllerAnimated:YES completion:nil];
}