Free On-Device Development

Now everyone can run and test their own app on a device—for free. You can run and debug your own creations on a Mac, iPhone, iPad, iPod touch, or Apple Watch without any fees, and no programs to join. All you need to do is enter your free Apple ID into Xcode. You can even use the same Apple ID you already use for the App Store or iTunes. Once you’ve perfected your app the Apple Developer Program can help you get it on the App Store.

See Launching Your App on Devices for detailed information about installing and running on devices.

Swift Language

Swift 2.0 takes the advanced object-oriented Swift programming language to the next level.

Swift 2.0 is modern, powerful, expressive, and easy to use. It extends Swift 1.2 with:

• Error handling. Now you can create routines that throw, catch, and manage errors in Swift. You can surface and deal with recoverable errors, such as “file-not-found” or network timeouts. Swift 2.0 error handling interoperates transparently with NSError.

• Availability. Availability features enable you to mark up methods with the OS that they are available on, providing compile time checking and preventing unavailable methods from being used. You can adopt new APIs while still deploying back to older OS versions. Compile-time errors are provided when you’re using an API that isn’t guaranteed to be available on the deployment target.

• Testability. With testability, you are now able to write tests of Swift 2.0 frameworks and apps without having to make all of your internal routines public. Use @testable import {ModuleName} in your test source code to make all public and internal routines usable by XCTest targets, but not by other framework and app targets.

• Protocol extensions. You can now add methods and properties to any class that conforms to a particular protocol, allowing you to reuse more of your code. For example, in the standard library, instead of having to use global functions for all of the generic algorithms in the standard library (such as map, filter, and sort), those generic algorithms are now available as methods on all of the collection types.

The Swift 1.2 to 2.0 migrator in Xcode 7 enables you to efficiently upgrade your existing Swift source code to take advantage of Swift 2.0.

The Swift migrator works with both projects and playgrounds.

See The Swift Programming Language to learn more about the Swift programming language, and check the Revision History chapter for pointers to the updated Swift features.

Objective-C Language

Objective-C has been updated to enable it and Swift to work together more easily and efficiently. The new Objective-C language features include:

• Generics. Allow you to specify type information for collection classes such as NSArray, NSSet, and NSDictionary. The type information improves Swift access when you bridge from Objective-C and simplifies the code you have to write.

• Nullability annotation. Lets you indicate in Objective-C source when to expect a value to be nil or non-nil, smoothing the use of Objective-C frameworks and modules from Swift code.

• KindOf. Objects declared as __kindof types express “some kind of X” to the compiler and can be used within generic parameters to constrain types to a particular class or its subclasses. Using __kindof allows constraints to be more flexible than an explicit class, and more explicit than just using id.

These new language features help the Objective-C/Swift interaction. They express more information to the compiler about your expectations in the code rather than in documentation, which provides a means for Xcode to inform you of problems earlier in the development cycle, before your code is run.

See Using Swift with Cocoa and Objective-C for detailed information on Objective-C language features and how they interact with Swift.

Playgrounds

Playgrounds, since their introduction with Swift in Xcode 6, have proven a great way to explore and prototype Swift code. With Swift 2.0, you can use playgrounds to help explain how to use an API or demonstrate a concept.

• Playground authoring. Rich comments let you explain what is going on in your Swift code. They provide a simple Markdown-like syntax to let you control their appearance and are visually differentiated from the code, making a playground appear to the user in smaller, more easily consumable pieces. For details on playground rich comments, see Playground Reference and look at the Playground Markup Format Reference.

• Inline results. You can move the display of your code’s results from the timeline area to directly below the code that produces them. This makes the result of a line of code clearer to your audience. Inline results are also more configurable than the display in the timeline.

• Resources. With the resource bundle, you can easily add images, sounds, and other data to your playground using the project navigator.

• Auxiliary sources. Auxiliary sources let you move supporting code out of a playground, which helps you keep the message of the playground clearer. Additionally, auxiliary sources are compiled and execute more quickly.

• Playground pages. New in Xcode 7, pages enable you to bundle related concepts together. A single playground can contain multiple, targeted pages, which lets you thread a narrative together.

See Playground Help for more information about using playground features.

App Thinning

With Xcode 7, you are developing apps for three diverse platforms that run on a variety of devices and configurations.

The devices can have widely different storage and display capabilities. You can deliver an optimized app to each platform device, supplying the functionality you intend without including unneeded resources, using new features supported in Xcode 7 and used by the iTunes App Store.

• Bitcode. When you archive for submission to the App Store, Xcode compiles your app into an intermediate representation. The App Store then compiles the bitcode down into the 64- or 32-bit executables as necessary.

• Slicing. Your artwork incorporated into the asset catalog can be tagged to indicate its suitability for the device that is targeted for installation when a user purchases and downloads your app onto their device. Xcode supports organizing and tagging in the asset catalog so that the App Store can perform the slicing operation automatically. End users get just the resources needed for their device.

• On-demand resources. For apps that need some content only after the initial download and installation, you can host the additional content for the app on the iTunes App Store repository. You tag these resources for their appropriate categories and control when these assets are downloaded. Xcode builds your app with information that allows it to fetch the resources when are needed, using asynchronous download and installation. See On-Demand Resources Guide for more information.

See App Thinning (iOS, watchOS) in App Distribution Guide for detailed information.

Debugging

Xcode 7 includes new debugging and profiling features targeted at helping you make better apps for your customers.

• Energy gauge for iOS. Xcode 7 brings insight into the energy usage of your iOS app with the energy gauge. iOS 9 has plumbed in the ability to track energy on a per-process basis, which is surfaced in the energy report. This is a great way to gain insight into how your app is affecting battery life. You can see unexpected behavior, such as high energy usage while your app should be just sitting idle or anomalous spikes in power consumption when you’re expecting a steady profile. Learn more about how to manage power for iOS apps in Energy Efficiency Guide for iOS Apps.

  The debug gauges and their reports provide quick insight into your running app. When you see situations occur that require more detailed analysis, each gauge’s report includes a means to launch your running app into Instruments. With Xcode 7, the Instruments redesigned track view and UI are natural and easy to interact with. Gestures like “pinch-to-zoom” make navigating through your data smooth and informative. More information on the latest Instruments is available from Instruments User Guide.

• Address sanitizer. Xcode 7 can build your app with instrumentation designed to catch and debug memory corruption using the address sanitizer.

  Objective-C and C code is susceptible to memory corruption issues such as stack and heap buffer overruns and use-after-free issues. When these memory violations occur, your app can crash unpredictably or display odd behavior. Memory corruption issues are difficult to track down because the crashes and odd behavior are often hard to reproduce, and the cause can be far from the origin of the problem.

  You enable the address sanitizer in the build scheme. Once enabled, added instrumentation is built into the app to catch memory violations immediately, enabling you to inspect the problem right at the place where it occurs. Other diagnostic information is provided as well, such as the relationship between the faulty address and a valid object on the heap and allocation/deallocation information, which helps you pinpoint and fix the problem quickly.

  The address sanitizer is efficient—fast enough to be used regularly as well as with interactive applications. It is supported in OS X, in the Simulator, and on iOS devices.

Testing

Xcode 7 introduces UI testing as a major new feature of the existing XCTest framework. UI testing is implemented as an extension to the existing APIs and concepts in XCTest, making it easy to adopt for developers who have familiarity with Xcode’s testing features.

• UI recording. Create your first UI test method by recording an interaction with your app. As you interact with your app, Xcode emits source code into your test method to find elements in the UI of your app, to access their properties, and to send them events.

• Correctness and performance. XCTest now offers a rich set of features for locating elements in the UI of your app, for accessing elements’ properties, and for synthesizing events. The UI testing support in XCTest integrates with existing features for asserting conditions that must be true and in using baselines to monitor the performance of your app over time and across different devices.

• Code coverage. Visualize the completeness of your test suite by enabling code coverage for your scheme. The code coverage pane in the test report shows which files, functions, and lines of code were exercised and, more importantly, which were not exercised. The source code editor can also show code coverage information inline, allowing you to see at a glance which lines—and parts of a line—the tests exercised.

• Xcode Server. Xcode testing features are designed to integrate completely with Xcode Server, with which you can run tests on multiple devices, repeatedly, in a hands-off environment that allows consistency and better evaluation of both correctness and performance. New Xcode Server report formatting shows trends and regressions over repeated tests of a project throughout your development process.

See Testing with Xcode for more information about testing your app using Xcode testing features.

Crash Logs

Xcode provides a way to analyze and use crash data submitted by users, with all the facilities of the debugger and your source code at hand.

Now, in Xcode 7, this feature is extended to include crash data from OS X apps, in addition to watchOS and iOS.

• TestFlight. You distribute your app for beta testing to selected testers before you ship to customers, giving you the ability to get real-world feedback. Users can also elect to share reports on crashes with the App Store, where they are collected and symbolicated.

• Crash reports. In the Xcode 7 Organizer window, click the Crashes tab to display a coalesced list of crash logs organized by the apps you’ve submitted. Each entry in the crash report tells you how often this crash was reported and where in the code it occurred. Click items in the crash report to present a historical backtrace of the crashed app, which you can transfer to the debug navigator and use to navigate directly to your source code in Xcode where the problem can be inspected and fixed.

See Analyzing Crash Reports in App Distribution Guide for more information.

Interface Builder

• Storyboards now support 3D Touch gestures such as Peek and Pop.

Debugging

• Swift error breakpoints can be created in the Xcode debugger.

  Swift errors activate defined Swift error breakpoints when the error is thrown. You can edit Swift error breakpoint so that they are activated only for a specified Swift error type.

Crashes Organizer

• The Xcode Crashes Organizer now displays crash reports originating from tvOS apps.

Deprecation and Removal Notice

• OS X 10.11 is the last major release of OS X that supports the previously deprecated garbage collection runtime.

  Applications or features that depend upon garbage collection may not function properly or may fail to launch when the runtime is removed. Developers should use Automatic Reference Counting (ARC) or manual retain/release for memory management instead.

• Apple private frameworks have been removed from the iOS, watchOS, and tvOS SDKs.

  If your app fails to link, make sure that you are not using any private frameworks. The use of private frameworks is an unsupported configuration and apps that use non-public APIs will be rejected by the App Store. For details, see App Store Guideline 2.5.