Offering, completing, and restoring in-app purchases

At a glance

Project structure

Source bundle/
├── Objective-C/
│   ├── iOS/
│   │   ├── main.m
│   │   └── ParentViewController.m
│   ├── macOS/
│   │   ├── main.m
│   │   ├── AppDelegate.m
│   │   └── MainViewController.m
│   ├── tvOS/
│   │   ├── main.m
│   │   └── TabBarViewController.m
│   └── Common/
│       ├── StoreManager.m
│       └── StoreObserver.m
└── Swift/
    ├── Common/
    │   └── AppProtocols.swift
    ├── iOS/
    │   └── ParentViewController.swift
    └── tvOS/
        └── TabBarViewController.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C/Objective-C header, Objective-C, Swift.
• The verified tree contains 27 project/configuration file(s) and 62 source declaration(s).

Overall architecture

flowchart LR
    Bundle["Sample bundle"]
    V1["Objective-C"]
    V2["Swift"]
    Boundary["StoreKit APIs"]
    Bundle --> V1
    V1 --> Boundary
    Bundle --> V2
    V2 --> Boundary

Reference code

Objective-C/iOS/main.m:11 — architecture anchor

int main(int argc, char * argv[]) {
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

Interpretation

The branches represent separate entry-bearing project variants in the downloaded bundle, not runtime calls between those variants. Each branch is intentionally collapsed at the documented framework boundary; the detailed target-local flow remains in the cited files. Ownership is claimed only where the next section cites a stored property or assignment.

Ownership and state

classDiagram
    StoreManager o-- NSMutableArray : availableProducts
    StoreManager o-- NSMutableArray : invalidProductIdentifiers
    StoreManager o-- SKProductsRequest : productRequest
    StoreObserver o-- BOOL : hasRestorablePurchases

Ownership evidence

Objective-C/Common/StoreManager.m:12 — stored dependency or nearest verified ownership anchor

@interface StoreManager()<SKRequestDelegate, SKProductsRequestDelegate>
// ...
@property (strong) NSMutableArray *availableProducts;
// ...
@end

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Concurrency, scheduling, and thread safety

Evidence limit: actor isolation, async/await, or Task creation does not by itself prove background-thread execution; Sendable conformance alone does not prove thread-safe mutation.

@MainActor/MainActor.run, DispatchQueue.main, and RunLoop.main are reported as distinct isolation, queue, and event-loop mechanisms. A plain Task is kept separate from Task.detached; neither is labeled as a background thread.

Reference code

Swift/Common/StoreManager.swift:108 — representative execution boundary

            DispatchQueue.main.async {
                self.delegate?.storeManagerDidReceiveResponse(self.storeResponse)
            }

State propagation, frameworks, and dependencies

Evidence limit: an import proves a source-level compilation dependency at the cited line; it does not prove runtime use, architectural adoption, or whether a Swift package is a direct application dependency.

receive(on:) describes downstream delivery scheduling, while subscribe(on:) describes upstream subscription/request/cancel scheduling. An import Combine alone establishes neither behavior nor a Store, reducer, Redux, or other application architecture.

Class and protocol design

Swift/Common/AppProtocols.swift:12 — representative type boundary

protocol DiscloseView {
    func show()
    func hide()
}

The source explicitly defines local protocol relationships: BaseViewController → IAPTableViewDataSource, NSView → DiscloseView, UIView → DiscloseView, UIBarItem → EnableItem, ParentViewController → StoreManagerDelegate, ParentViewController → StoreObserverDelegate.

Access control

Reference code

Objective-C/Common/BaseViewController.h:12 — representative boundary

@interface BaseViewController : UITableViewController <IAPTableViewDataSource>
@property (strong) NSMutableArray *data;
@end

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Design patterns

Main application flow

sequenceDiagram
    participant StoreManager
    participant storeResponse
    participant NSMutableArray
    participant Section
    participant NSNotificationCenter
    StoreManager->>storeResponse: removeAllObjects()
    StoreManager->>NSMutableArray: arrayWithArray()
    StoreManager->>Section: initWithName()
    StoreManager->>storeResponse: addObject()
    StoreManager->>NSMutableArray: arrayWithArray()
    StoreManager->>Section: initWithName()
    StoreManager->>storeResponse: addObject()
    StoreManager->>NSNotificationCenter: postNotificationName()

Reference code

Objective-C/Common/StoreManager.m:82 — productsRequest()

- (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response {
    if (self.storeResponse.count > 0) {
        [self.storeResponse removeAllObjects];
    }

    // Contains products with identifiers that the App Store recognizes. As such, they are available for purchase.
    if ((response.products).count > 0) {
        self.availableProducts = [NSMutableArray arrayWithArray:response.products];
        Section *section = [[Section alloc] initWithName:PCSProductsAvailableProducts elements:response.products];
        [self.storeResponse addObject:section];
    }

    // invalidProductIdentifiers contains all product identifiers that the App Store doesn’t recognize.
    if ((response.invalidProductIdentifiers).count > 0) {
        self.invalidProductIdentifiers = [NSMutableArray arrayWithArray:response.invalidProductIdentifiers];
        Section *section = [[Section alloc] initWithName:PCSProductsInvalidIdentifiers elements:response.invalidProductIdentifiers];
        [self.storeResponse addObject:section];
    }

    if (self.storeResponse.count > 0) {
        self.status = PCSStoreResponse;

        dispatch_async(dispatch_get_main_queue(), ^{
            [[NSNotificationCenter defaultCenter] postNotificationName:PCSProductRequestNotification object:self];
        });
    }
}

Naming conventions

• Types: Controller: BaseViewController, MainViewController, MessagesViewController, ParentViewController, PrimaryViewController; DataSource: IAPTableViewDataSource; Delegate: AppDelegate, SettingsDelegate, StoreManagerDelegate, StoreObserverDelegate; Manager: StoreManager; Observer: StoreObserver; View: DiscloseView.
• Protocols: DiscloseView, StoreManagerDelegate, StoreObserverDelegate, SettingsDelegate, IAPTableViewDataSource, EnableItem.
• Methods: sharedInstance, init, startProductRequestWithIdentifiers, fetchProductsMatchingIdentifiers, productsRequest, request, titleMatchingIdentifier, titleMatchingPaymentTransaction.
• Files: Objective-C/Common/StoreManager.m, Objective-C/Common/StoreObserver.m, Objective-C/iOS/ParentViewController.m, Objective-C/macOS/AppDelegate.m, Objective-C/macOS/MainViewController.m, Objective-C/tvOS/TabBarViewController.m.

Architecture takeaways

• main is the main source-visible entry or composition anchor for this sample.
• Framework work reaches StoreKit, UIKit, Cocoa through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
• Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
• Access-control conclusions separate verified language visibility from the likely design rationale.
• Local protocol relationships provide an explicit substitution boundary.

Source map

• Official Apple documentation