iOS SDK Migration Service: Update Your App for App Store Compliance

Noted: when you submit your latest build to the App Store, an hour later an email arrives: "ITMS-91053: Missing Privacy Manifest." With every new iOS SDK version, Apple deprecates old APIs and introduces mandatory requirements. Without planned migration, you risk being unable to submit updates. We frequently encounter these scenarios and offer end-to-end migration — including audit, update, and guarantee.

What Actually Breaks When Changing SDKs

Deprecated APIs are the most extensive part of the work. UIWebView has been removed since the iOS 15 SDK; apps using it receive rejection with ITMS-90809. UIAlertView, UIActionSheet, shouldAutorotateToInterfaceOrientation — these methods no longer compile in the iOS 16 SDK. We search the codebase via Xcode #available and the deprecated list from the specific SDK release notes.

Privacy Manifest (iOS 17 SDK) — a new requirement from recent versions. Every third-party dependency and the app itself must include a PrivacyInfo.xcprivacy file declaring the used API categories (NSPrivacyAccessedAPITypes): NSUserDefaults, NSFileManager, NSProcessInfo, UIDevice.systemBootTime. If the file is missing, ITMS-91053 appears as a warning (now an error) during submission.

Example PrivacyInfo.xcprivacy:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" ...>
<plist version="1.0">
<dict>
    <key>NSPrivacyAccessedAPITypes</key>
    <array>
        <dict>
            <key>NSPrivacyAccessedAPIType</key>
            <string>NSPrivacyAccessedAPICategoryUserDefaults</string>
            <key>NSPrivacyAccessedAPITypeReasons</key>
            <array>
                <string>CA92.1</string>
            </array>
        </dict>
    </array>
</dict>
</plist>

Reasons must be specific codes from Apple's documentation. CA92.1 for UserDefaults means "storage of settings directly managed by the user." You can't just write any code — you must choose from the approved list. If none fit, you need to write to Apple via App Review, which is a challenge in itself.

Swift Concurrency and Sendable — iOS 16+ SDK includes enhanced Sendable checks and actor isolation. A project that built without warnings on an older SDK will produce dozens of warnings like Capture of non-Sendable type 'SomeModel' on the new SDK. With iOS 17 SDK, some become errors when strict concurrency checking: complete is enabled. On large codebases, this is a significant effort.

How We Perform the Migration

1. Audit via xcodebuild

   xcodebuild -workspace MyApp.xcworkspace \
              -scheme MyApp \
              -destination 'generic/platform=iOS' \
              -sdk iphoneos17.0 \
              build 2>&1 | grep -E "error:|warning:" | sort | uniq -c | sort -rn | head -50
   

   This provides a quantitative picture: how many errors, which categories, top 50 by frequency. For a 300k line codebase jumping from iOS 14 SDK to iOS 17 SDK, typical results are 15–40 errors and 100–300 warnings. Our automated audit approach is 10–15 times faster than manual code review.

2. Analysis of Third-Party Dependencies The second issue is libraries that haven't been updated in two years. Our checklist:

   • CocoaPods: pod outdated for a list of outdated dependencies
   • SPM: check Package.resolved, look for libraries without recent tags on GitHub
   • Dependencies with outdated deployment target — conflicts with the app's new minimum iOS version

   A special case is dependencies without a Privacy Manifest. Apple requires manifests from popular SDKs (Firebase, Crashlytics, Amplitude, Adjust, and others have updated their packages). But for lesser-known libraries, the manifest may be missing, requiring either forking and adding it or removing the dependency.

3. Migration by Complexity Levels

   Category of Changes	Effort
   Replace UIWebView → WKWebView	Medium (delegate API changes)
   Privacy Manifests for custom code	Low (configuration)
   Privacy Manifests for third-party SDKs	Depends on author support
   Sendable/actor isolation warnings	High (architectural changes)
   Removed APIs (UIAlertView etc.)	Low (direct replacement)

What's Included in Our Work

• Full codebase audit with xcodebuild and identification of all blocked APIs
• Configuration of Privacy Manifest for the app and all dependencies
• Updating third-party SDKs to versions compatible with the new iOS SDK
• Fixing Sendable/actor isolation warnings
• Testing on real devices with the new iOS version
• Documentation of changes and recommendations for ongoing support
• 30-day guarantee after delivery

How We Test After Migration

Smoke tests on a real device with the new iOS are mandatory. Simulator and real device can behave differently when changing SDKs, especially regarding URLSession timeouts, push notifications, and background execution.

Crashlytics or Firebase Crash Reporting — after release we monitor new crash signatures in the first 24–48 hours. SDK migration sometimes introduces crashes in edge cases not covered by tests.

Timeline Estimates

Timelines depend on codebase size, number of deprecated APIs, and dependency state:

Cost is calculated individually, but you save by catching issues early — migration costs are always lower than the consequences of blocked releases. Contact us for an accurate assessment. With experience migrating over 50 projects, we guarantee to account for all pitfalls. Get a consultation for your codebase — we'll conduct an audit in one day.

Apple App Store Review Guidelines

Why is Native iOS Development the Best Choice for Complex Apps

The app crashes on cold start — EXC_BAD_ACCESS at the moment of initializing a singleton that accesses another singleton that hasn't been initialized yet. Or: a ViewController leaks memory because a closure captures self without [weak self], and that ViewController hangs in memory two transitions after the user left it. These are not hypothetical scenarios — they are the two most common classes of problems on iOS projects that come to us after another team.

We have been doing iOS development for over 5 years, delivered 40+ projects of varying complexity — from startups to enterprise solutions with millions of users. Each project undergoes 3 stages of Code Review, a custom set of UI tests (150+ test cases on average), and a mandatory run through Xcode Instruments before release.

Native iOS development with Swift means direct access to the platform. No middleware, no performance compromises, full control over what happens on every frame.

What Makes Native iOS Development on Swift the Choice for Enterprise Apps?

Native code guarantees compatibility with new Apple APIs on the day they are released, not after months of adaptation in cross-platform frameworks. For apps with latency-sensitive logic (financial terminals, medical monitors, AR navigation), this is critical. Swift with ARC and strict typing allows maintaining a crash-free rate of 99.9% with proper architecture.

SwiftUI or UIKit: What to Choose for Native iOS Development

By now, SwiftUI covers the vast majority of production tasks. But UIKit is not deprecated and will not disappear — Apple does not deprecate it but continues to add APIs. The real picture on large projects: a hybrid approach. SwiftUI for most screens, UIKit where SwiftUI hits limitations.

Which Scenarios Does SwiftUI Win Unconditionally

SwiftUI's declarative syntax reduces UI code by 3-5 times compared to UIKit. A settings screen with List, Toggle, Picker — that's 40 lines of SwiftUI versus 200 lines of UIKit with UITableViewDataSource delegates. Time savings on UI development reach 60%. Apple recommends starting new projects on SwiftUI (Human Interface Guidelines).

@State, @Binding, @ObservableObject (and with iOS 17, the @Observable macro) create a reactive link between data and UI without manual reloadData(). Changing a @State variable automatically redraws the affected part of the hierarchy. This works correctly if you understand how SwiftUI computes the diff — via Equatable and id in ForEach.

AsyncImage, NavigationStack with type-safe routing via NavigationPath, searchable, refreshable — these are ready-made patterns that UIKit requires implementing manually.

When UIKit Remains Necessary

UICollectionView with compositional layout and diffable data source — complex grids with different cell types, horizontal sections inside vertical scroll, dynamic cell sizes. SwiftUI LazyVGrid / LazyHGrid do not provide such control.

Custom transitions between screens. UIViewControllerAnimatedTransitioning and UIViewControllerInteractiveTransitioning — interactive pop gesture with partial progress, custom hero transition with precise frame control. SwiftUI matchedGeometryEffect covers some cases, but not all.

UITextView with TextKit 2. Rich text editor, custom attributes, custom rendering — TextKit 2 (available since iOS 16) switched to async layout, solving performance issues on long documents. SwiftUI TextEditor is a wrapper around UITextView without direct access to TextKit.

UIScrollView with custom behavior. scrollViewDidScroll, parallax effects, sticky headers with custom logic, pull-to-refresh with custom indicator. SwiftUI ScrollView with scrollPosition and onScrollGeometryChange (iOS 17) covers some cases, but not all.

How Do We Integrate SwiftUI and UIKit Step by Step

1. Identify screens where SwiftUI gives maximum gain (lists, forms, settings) — usually 70-80% of screens.
2. For performance-critical areas (complex collections, custom animations) leave UIKit.
3. Use UIHostingController to embed SwiftUI views into UIKit navigation stack.
4. For backward compatibility, wrap UIKit components via UIViewRepresentable.
5. Coordinator pattern (UIKit) manages navigation at the flow level, screens are implemented in SwiftUI.

One pattern we use on projects: UIKit coordinator manages navigation, while the screens themselves are in SwiftUI. The coordinator creates a UIHostingController, passes ViewModel via initializer or @EnvironmentObject, and manages transitions. This gives clean separation: SwiftUI handles UI, Coordinator handles navigation.

How async/await and Combine Work Together

Before Swift 5.5, asynchronous code on iOS was built on Combine or callback chains. With the advent of async/await and Actor, concurrency has become part of the language. On new projects we use async/await as the primary tool for network calls and business logic, and Combine for reactive UI state binding.

// Correct — @MainActor guarantees UI updates on main thread
@MainActor
class UserViewModel: ObservableObject {
    @Published var user: User?
    @Published var isLoading = false

    func loadUser(id: String) async {
        isLoading = true
        defer { isLoading = false }
        do {
            user = try await userService.fetch(id: id)
        } catch {
            // handle error
        }
    }
}

Combine remains indispensable for debouncing input, merging multiple Publishers (CombineLatest, Zip), and functional processing of value streams (map, flatMap, filter). In practice, 80% of projects use both approaches, choosing the tool for the task.

iOS App Architecture

MVVM — the basic pattern. ViewModel contains logic and @Published state, SwiftUI View subscribes via @ObservedObject or @StateObject. One rule: View knows nothing about URLSession, CoreData, UserDefaults.

Clean Architecture adds Repository and UseCase layers. UserRepository abstracts the data source (network vs cache). FetchUserUseCase contains business logic. UserViewModel calls UseCase and manages UI state.

TCA (The Composable Architecture) — a stricter pattern from Point-Free. State, Action, Reducer, Effect — everything explicit, testable, composable via Scope. Works well in large teams (5+ iOS developers) where predictability is important.

What's Included in iOS App Development

Tools Without Which No Release Is Complete

Xcode Instruments. Time Profiler shows where CPU spends time. Allocations — memory leaks and excessive allocations. Leaks — objects that are not freed. Before every release — a mandatory run.

Firebase Crashlytics. Crash-free rate, grouping by stack trace, breadcrumbs of events leading to crash. Set up in 30 minutes, provides visibility across the entire device fleet. On our projects, average crash-free rate is 99.8%.

Fastlane match. Manage certificates and provisioning profiles via an encrypted git repository. Eliminates the 'it builds locally but not on CI' issue once and for all. Saves up to 4 hours per build when signing manually.

XCTest + XCUITest. Unit tests for ViewModel and UseCase, UI tests for critical flows (onboarding, payment, authorization). On average, code coverage is 75%.

Process and Timelines

Cost is calculated individually after analyzing the technical specification and design. Typically, the first 2 weeks are spent on design, after which we finalize the timeline and budget.

Order turnkey development — we will evaluate your project in 2 business days and propose the optimal architecture. Contact us to discuss your task: we guarantee code quality, compliance with App Store Review Guidelines, and experience with projects of any scale. Get a consultation — we will help you choose the right stack and avoid common mistakes at the start.