Apple App Store Viewer (iOS 6+)

CMInfoAppStoreViewer.h

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

@interface CMInfoAppStoreViewer : NSObject

- (void)displayAppStoreForApp:(CMAppType)app withNavigationController:(UINavigationController *)navigationController;
- (void)displayAppStoreForAppId:(NSNumber *)appNumber iTunesURL:(NSURL *)itunesURL withNavigationController:(UINavigationController *)navigationController;

@end

CMInfoAppStoreViewer.m

#import "CMInfoAppStoreViewer.h"
#import <UIKit/UIKit.h>
#import <StoreKit/StoreKit.h>
#import "WorkingOverlayView.h"
#import "NSURL+AppStoreURL.h"

@interface CMInfoAppStoreViewer() <SKStoreProductViewControllerDelegate, UIAlertViewDelegate>
@property (nonatomic, strong) SKStoreProductViewController *productController;
@property (nonatomic, strong) CMWorkingOverlayViewPresenter *overlayPresenter;
@property (nonatomic, assign, getter=isCancelled) BOOL cancelled;
@end

@implementation CMInfoAppStoreViewer

- (void)displayAppStoreForApp:(CMAppType)app withNavigationController:(UINavigationController *)navigationController
{
    //FIXME: JC - although this is in one place, it could be improved.
    NSNumber *appNumber = nil;
    NSString *appURL = nil;
    switch (app)
    {
        case CMAppTypeSeoul:
        {
            appNumber = @(343491689);
            appURL = @"/us/app/seoul-city-metro-seoul-south/id343491689";
            break;
        }
        case CMAppTypeSeoulLite:
        {
            appNumber = @(356066122);
            appURL = @"/us/app/seoul-city-metro-lite-seoul/id356066122";
            break;
        }
        case CMAppTypeBusan:
        {
            appNumber = @(356337150);
            appURL = @"/us/app/busan-city-metro-south-korean/id356337150";
            break;
        }
        case CMAppTypeDelhi:
        {
            appNumber = @(377654366);
            appURL = @"/us/app/delhi-city-metro-xix-commonwealth/id377654366";
            break;
        }
        case CMAppTypeDubai:
        {
            appNumber = @(400118556);
            appURL = @"/us/app/dubai-city-metro/id400118556";
            break;
        }
    }

    [self displayAppStoreForAppId:appNumber
                        iTunesURL:[NSURL appStoreURLWithPath:appURL]
         withNavigationController:navigationController];
}

- (void)displayAppStoreForAppId:(NSNumber *)appNumber iTunesURL:(NSURL *)itunesURL withNavigationController:(UINavigationController *)navigationController
{
    NSParameterAssert(appNumber);
    NSParameterAssert(itunesURL);
    NSAssert([navigationController isKindOfClass:[UINavigationController class]], @"Refernce must be a UINavigationController");

    WorkingOverlayView *workingOverlayView = [WorkingOverlayView overlayView];
    [workingOverlayView setText:NSLocalizedString(@"RootView.UpgradeCell.LoadingAppStoreMessage", @"Loading App Store Message after tapping the cell")];
    self.overlayPresenter = [[CMWorkingOverlayViewPresenter alloc] init];

    __weak CMWorkingOverlayViewPresenter *weak_pesenter = self.overlayPresenter;
    __weak __typeof(self) weak_self = self;
    self.overlayPresenter.overlayTapBlock = ^{
        weak_self.cancelled = YES;
        [weak_pesenter dismissOverlayViewAnimated:YES];
    };

    self.productController = [[SKStoreProductViewController alloc] initWithNibName:nil bundle:nil];
    self.productController.delegate = self;

    __weak __typeof(self.productController) weak_productController = self.productController;

    NSDictionary *params = @{ SKStoreProductParameterITunesItemIdentifier: appNumber };
    [self.productController loadProductWithParameters:params completionBlock:^(BOOL result, NSError *error) {

        [weak_self.overlayPresenter dismissOverlayViewAnimated:NO];

        if (result)
        {
            if (!weak_self.isCancelled)
            {
                [navigationController presentViewController:weak_productController animated:YES completion:nil];
            }
        }
        else
        {
            if ([[UIApplication sharedApplication] canOpenURL:itunesURL])
            {
                [[UIApplication sharedApplication] openURL:itunesURL];
            }
            else
            {
                UIAlertView *alert = [[UIAlertView alloc]initWithTitle:NSLocalizedString(@"Error",@"Error Message Title")
                                                               message:NSLocalizedString(@"no appstore message",@"The App Store is not available from your device.")
                                                              delegate:weak_self
                                                     cancelButtonTitle:NSLocalizedString(@"Dismiss",@"Dismiss Button Title")
                                                     otherButtonTitles:nil];
                [alert show];
            }
        }
    }];

    [self.overlayPresenter presentOverlayView:workingOverlayView insideView:navigationController.view];
}

#pragma mark - SKStoreProductViewControllerDelegate

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

#pragma mark - UIAlertVieDelegate

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
    [self.overlayPresenter dismissOverlayViewAnimated:YES];
}

@end

NSURL+AppStoreURL.h

#import <Foundation/Foundation.h>

@interface NSURL (AppStoreURL)

+ (NSURL *)appStoreURLWithPath:(NSString *)path;

@end

NSURL+AppStoreURL.m

#import "NSURL+AppStoreURL.h"

@implementation NSURL (AppStoreURL)

+ (NSURL *)appStoreURLWithPath:(NSString *)path
{
    NSURLComponents *urlComps = [[NSURLComponents alloc] init];
    urlComps.host = @"itunes.apple.com";
    urlComps.path = path;

    if (NSFoundationVersionNumber >NSFoundationVersionNumber_iOS_7_1)
    {
        urlComps.scheme = @"https";
        NSURLQueryItem *mtQUeryItem = [NSURLQueryItem queryItemWithName:@"mt" value:@"8"];
        urlComps.queryItems = @[mtQUeryItem];
    }
    else
    {
        urlComps.scheme = @"itms";
        urlComps.query = @"mt=8";
    }

    return [urlComps URL];
}

@end