Making Store Purchases in iOS with the SKStoreProductViewController Class

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For quite some time, the iOS SDK has included the Store Kit Framework, the purpose of which is to enable applications to implement what are referred to as “in-app purchases”. This typically provides a mechanism for application developers to charge users for additional items and services over and above the initial purchase price of the application. Typical examples include purchasing access to higher levels in a game or a monthly subscription to premium content.

The Store Kit Framework has also traditionally provided the ability to enable users to purchase items from Apple’s iTunes, App and iBook stores. Prior to the introduction of iOS 6, the Store Kit Framework took the user out of the current application and into the iTunes application to initiate and complete an iTunes Store purchase. iOS 6, however, introduced a view controller class (SKStoreProductViewController) which presents the store product directly within the application using a pre-configured view.

This chapter will provide an overview of the SKStoreProductViewController class before working through an example implementation of this class in an iOS application.




The SKStoreProductViewController Class

The SKStoreProductViewController class makes it possible to integrate purchasing from Apple’s iTunes, App and iBooks stores directly into iOS applications with minimal coding work. The developer of a music review application, might, for example want to provide the user with the option to purchase an album from iTunes after reading a review in the application. The developer of multiple applications may want to encourage users of one of those applications to purchase related applications.

All that is required to implement the SKStoreProductViewController functionality is to initialize an instance of the class with an item ID for the product to be purchased from the store and then to load the product details. Once product details have been loaded, the view controller is presented to the user.

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Product item IDs can be obtained a number of ways. For specific items, the ID can be obtained by locating the product in iTunes and Ctrl-clicking (or right-clicking on Windows) on the product image. In the resulting menu, select the option to copy the URL. Paste the URL into a text editor and extract the ID from the end. The ID from the following URL, for example, is 527049179.

http://itunes.apple.com/us/movie/the-pirates!-band-of-misfits/id527049179

Alternatively, searches may be performed on a variety of criteria using the Apple Search API, details of which can be found at the following URL:

http://www.apple.com/itunes/affiliates/resources/documentation/itunes-store-web-service-search-api.html

When the user has finished in the store view, a delegate method is called to notify the application, at which point the store view controller can be dismissed.

The remainder of this chapter will work through the creation of a simple example application to demonstrate the use and implementation of the SKStoreProductViewController class.

Creating the Example Project

The example application created in this chapter will consist of a single button which, when touched, will display the store kit view controller primed with a specified product. Launch Xcode and create a new project by selecting the options to create a new iOS application based on the Single View Application template. Enter StoreKitDemo as the product name, choose Swift as the programming language and set the Devices menu to Universal.


Creating the User Interface

Within the project navigator panel, select the Main.storyboard file and drag and drop a Button from the Object Library to the center of the view. Double-click on the button text and change it to “Buy Now” so that the layout matches Figure 106-1. With the Button view selected, display the Auto Layout Align menu and enable the horizontal and vertical in Container constraints.

Display the Assistant Editor and make sure it is showing the code for the ViewController.swift file. Select the button in the view and then Ctrl-click on it and drag the resulting line to a location just beneath the viewDidLoad method in the Assistant Editor panel. Release the line and in the resulting panel change the connection type to Action and name the method showStoreView. Click on the Connect button and close the Assistant Editor panel.


Ios 10 storekit demo ui.png

Figure 106-1

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Displaying the Store Kit Product View Controller

When the user touches the Buy Now button, the SKStoreProductViewController instance needs to be created, configured and displayed. Before writing this code, however, it will be necessary to declare the StoreKitDemoViewController class as implementing the SKStoreProductViewControllerDelegate protocol. The StoreKit framework also needs to be imported. Both of these tasks need to be performed in the ViewController.swift file which should be modified to read as follows:

import UIKit
import StoreKit

class ViewController: UIViewController, 
	SKStoreProductViewControllerDelegate {
.
.
.

Remaining within the ViewController.swift file, locate the stub showStoreView method and implement the code as outlined in the following listing:

@IBAction func showStoreView(_ sender: AnyObject) {
    let storeViewController = SKStoreProductViewController()
    storeViewController.delegate = self

    let parameters = [SKStoreProductParameterITunesItemIdentifier :
                        NSNumber(value: 676059878)]

    storeViewController.loadProduct(withParameters: parameters,
                completionBlock: {result, error in
        if result {
            self.present(storeViewController,
                        animated: true, completion: nil)
        }
    })
}

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Purchase the full iOS 10 / Swift 3 / Xcode 8 edition of this book in eBook ($19.99) or Print ($45.99) format.
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The code begins by creating and initializing a new SKStoreProductViewController instance:

let storeViewController = SKStoreProductViewController()

Next, the view controller class assigns itself as the delegate for the storeViewController instance:

storeViewController.delegate = self

A Dictionary is then created and initialized with a key of SKStoreProductParameterITunesItemIdentifier associated with an NSNumber value representing a product in a Store (in this case an album in the iTunes store).

let parameters = [SKStoreProductParameterITunesItemIdentifier :
                        NSNumber(value: 676059878)]

Finally, the product is loaded into the view controller and, in the event that the load was successful, the view controller is presented to the user:

storeViewController.loadProduct(withParameters: parameters,
            completionBlock: {result, error in
    if result {
        self.present(storeViewController,
                        animated: true, completion: nil)
    }
})

Implementing the Delegate Method

All that remains is to implement the delegate method that will be called when the user has either completed or cancelled the product purchase. Since the StoreKitDemoViewController class was designated as the delegate for the SKStoreProductViewController instance, the method needs to be implemented in the ViewController.swift file:

func productViewControllerDidFinish(_ viewController: SKStoreProductViewController) {
    viewController.dismiss(animated: true, completion: nil)
}

For the purposes of this example, all the method needs to do is to tell the view controller to dismiss itself.

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Purchase the full iOS 10 / Swift 3 / Xcode 8 edition of this book in eBook ($19.99) or Print ($45.99) format.
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Testing the Application

Build and run the application on a physical iOS device. Touch the button and wait until the store kit product view controller appears as illustrated in Figure 106-2. Note that there may be a short delay while the store kit contacts the iTunes store to request and download the product information.

Touching the Cancel button should trigger the delegate, dismissing the view controller and returning the user to the original view controller screen containing the button.


Ios 9 storekit ui.png

Figure 106-2

Summary

The SKStoreProductViewController class provides an easy and visually appealing interface for allowing Apple-based store purchases such as movies, books, music and apps to be made directly from within an iOS application. As demonstrated, this functionality can be added to an application with a minimal amount of code.


You are reading a sample chapter from the iOS 10 App Development Essentials book.

Purchase the full iOS 10 / Swift 3 / Xcode 8 edition of this book in eBook ($19.99) or Print ($45.99) format.
iOS 10 App Development Essentials Print and eBook (ePub/PDF/Kindle) edition contains over 100 chapters. Learn more...

Buy eBook Buy Print Preview Book



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An iOS 10 Twitter Integration Tutorial using SLRequestBuilding In-App Purchasing into iOS 10 Applications