How to implement in app purchase in iphone

6. Create a single view application and enter the bundle identifier is the identifier specified in iTunes connect.

7. Update the ViewController.xib as shown below.

8. Create IBOutlets for the three labels and the button naming them as productTitleLabel, productDescriptionLabel, productPriceLabel and purchaseButton respectively.

9. Select your project file, then select targets and then add StoreKit.framework.

10. Update ViewController.h as follows.

#import <UIKit/UIKit.h>
#import <StoreKit/StoreKit.h>

@interface ViewController : UIViewController<
SKProductsRequestDelegate,SKPaymentTransactionObserver>
{
    SKProductsRequest *productsRequest;
    NSArray *validProducts;
    UIActivityIndicatorView *activityIndicatorView;
    IBOutlet UILabel *productTitleLabel;
    IBOutlet UILabel *productDescriptionLabel;
    IBOutlet UILabel *productPriceLabel;
    IBOutlet UIButton *purchaseButton;
}
- (void)fetchAvailableProducts;
- (BOOL)canMakePurchases;
- (void)purchaseMyProduct:(SKProduct*)product;
- (IBAction)purchase:(id)sender;

@end

11. Update ViewController.m as follows.

#import "ViewController.h"
#define kTutorialPointProductID 
@"com.tutorialPoints.testApp.testProduct"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Adding activity indicator
    activityIndicatorView = [[UIActivityIndicatorView alloc]
    initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    activityIndicatorView.center = self.view.center;
    [activityIndicatorView hidesWhenStopped];
    [self.view addSubview:activityIndicatorView];
    [activityIndicatorView startAnimating];
    //Hide purchase button initially
    purchaseButton.hidden = YES;
    [self fetchAvailableProducts];    
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)fetchAvailableProducts{
    NSSet *productIdentifiers = [NSSet 
    setWithObjects:kTutorialPointProductID,nil];
    productsRequest = [[SKProductsRequest alloc] 
    initWithProductIdentifiers:productIdentifiers];
    productsRequest.delegate = self;
    [productsRequest start];
}

- (BOOL)canMakePurchases
{
    return [SKPaymentQueue canMakePayments];
}
- (void)purchaseMyProduct:(SKProduct*)product{
    if ([self canMakePurchases]) {
        SKPayment *payment = [SKPayment paymentWithProduct:product];
        [[SKPaymentQueue defaultQueue] addTransactionObserver:self];
        [[SKPaymentQueue defaultQueue] addPayment:payment];
    }
    else{
        UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:
        @"Purchases are disabled in your device" message:nil delegate:
        self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
        [alertView show];
    }
}
-(IBAction)purchase:(id)sender{
    [self purchaseMyProduct:[validProducts objectAtIndex:0]];
    purchaseButton.enabled = NO; 
}

#pragma mark StoreKit Delegate

-(void)paymentQueue:(SKPaymentQueue *)queue 
 updatedTransactions:(NSArray *)transactions {
    for (SKPaymentTransaction *transaction in transactions) {
        switch (transaction.transactionState) {
            case SKPaymentTransactionStatePurchasing:
                    NSLog(@"Purchasing");
                break;                
            case SKPaymentTransactionStatePurchased:
               if ([transaction.payment.productIdentifier 
                  isEqualToString:kTutorialPointProductID]) {
                   NSLog(@"Purchased ");
                   UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:
                   @"Purchase is completed succesfully" message:nil delegate:
                   self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
                   [alertView show];
                }               
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                break;                
            case SKPaymentTransactionStateRestored:               
                NSLog(@"Restored ");               
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                break;                
            case SKPaymentTransactionStateFailed:
                NSLog(@"Purchase failed ");
                break;
            default:
                break;
        }
    }
}

-(void)productsRequest:(SKProductsRequest *)request 
 didReceiveResponse:(SKProductsResponse *)response
{
    SKProduct *validProduct = nil;
    int count = [response.products count];
    if (count>0) {
        validProducts = response.products;
        validProduct = [response.products objectAtIndex:0];
        if ([validProduct.productIdentifier 
           isEqualToString:kTutorialPointProductID]) {
            [productTitleLabel setText:[NSString stringWithFormat:
            @"Product Title: %@",validProduct.localizedTitle]];
            [productDescriptionLabel setText:[NSString stringWithFormat:
            @"Product Desc: %@",validProduct.localizedDescription]];
            [productPriceLabel setText:[NSString stringWithFormat:
            @"Product Price: %@",validProduct.price]];           
        }        
    } else {
        UIAlertView *tmp = [[UIAlertView alloc]
                            initWithTitle:@"Not Available"
                            message:@"No products to purchase"
                            delegate:self
                            cancelButtonTitle:nil
                            otherButtonTitles:@"Ok", nil];
        [tmp show];
    }    
    [activityIndicatorView stopAnimating];
    purchaseButton.hidden = NO;
}

@end

Note:

You have to update kTutorialPointProductID to the productID you created for your In-App Purchase. You can add more than one product by updating the productIdentifiers's NSSet in fetchAvailableProducts. Similary handle purchase related actions for product IDs you add.

Output

Now when we run the application we'll get the following output.

Ensure you had logged out of your account in settings screen. On clicking Initiate Purchase select Use Existing Apple ID. Enter your valid test account username and password. You will be shown the following alert in a few seconds.