iOS 13 was a major developer release centered on SwiftUI, Dark Mode, Sign in with Apple, and advances to ARKit 3 and Core ML 3. For development work, treat it as both a framework and interface milestone: review Apple’s release notes for the exact SDK and OS version you target, then evaluate how the design changes affect your app.
What iOS 13 changed for app developers
Apple’s September 10, 2019 announcement highlighted Dark Mode, Sign in with Apple, and advances in ARKit 3, Core ML 3, and Siri as capabilities for iOS 13 apps. These are useful signposts for understanding the release, not a complete implementation guide; feature-specific behavior and availability should be checked in Apple’s documentation for the relevant API.
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The iOS 13 SDK was bundled with Xcode 11. Apple’s release notes advise developers to update apps for new features and test against API changes. The notes cover new features, deprecations, and known issues, so a broad feature summary cannot replace checking the entries relevant to your deployment and SDK versions.
SwiftUI: a new way to build interfaces
SwiftUI was one of the central developer topics in Apple’s WWDC 2019 platform material. Apple’s session catalog included Introducing SwiftUI: Building Your First App, SwiftUI Essentials, and Integrating SwiftUI. The platform overview provides context, while the sessions and Apple’s documentation are the right places to learn framework details; this overview is not a SwiftUI API reference.
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When assessing SwiftUI for an existing app, consider the UI architecture and OS versions the app needs to support. Apple’s iOS 13 release notes record SwiftUI changes, deprecations, and known issues, including a weak-linking workaround for apps that need to run on earlier OS versions without SwiftUI. Consult the exact release-note entry rather than assuming every issue applied to every final OS release.
Dark Mode and the broader interface update
Dark Mode was not simply a switch to add to settings. Apple’s design session says apps should respond when people enable it and discusses adapting colors, images, and text. Review the complete interface in both appearances, including screens and assets that may have been designed around a light background.
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The same session covers card-style modal sheets and contextual menus. Taken together, these changes call for a review of both visual appearance and interaction patterns—not just a new appearance toggle. Apple’s What’s New in iOS Design session is the source for this design guidance.
Sign in with Apple, ARKit 3, and Core ML 3
Apple’s announcement names Sign in with Apple, ARKit 3, and Core ML 3 among the iOS 13-era capabilities. That establishes their relevance to the release, but does not provide enough detail to explain entitlements, API behavior, availability by OS version, or implementation steps. Before adopting any of them, consult the feature-specific Apple documentation and release notes for the exact target environment.
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How to check compatibility and API changes
- Identify the versions that matter. Write down the SDK used to build the app and the OS versions it must support.
- Read the matching release notes. Apple’s iOS 13 Release Notes list changes, deprecations, and known issues. Check the specific entry and version rather than generalizing from a beta-specific note.
- Test the affected app paths. Exercise the features and interfaces your app uses against the API changes relevant to its targets. For SwiftUI back-deployment questions, verify Apple’s documented workaround and limitations.
- Use session material for design and framework context. Apple’s Platforms State of the Union — WWDC19 gives the platform overview, and the design session covers appearance and interaction changes.
One concrete release-note example is that UIApplicationExitsOnSuspend is no longer supported. This is a reason to inspect the notes for APIs your own app uses, not evidence that an unrelated app will be affected.
The April 2020 App Store requirement was historical
Apple’s September 10, 2019 announcement said that starting in April 2020, new apps and app updates would need to be built with the iOS 13 SDK and support the all-screen design of iPhone XS Max or later. That was a dated requirement announced in 2019; it should not be presented as today’s submission policy. Check Apple’s current App Store requirements before making a present-day compliance decision.
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