Migrate to Swift 4
How to Migrate to Swift 4?
Arun Kumar
Category: Mobile App

Recently, Apple released Swift 4 with several new features and enhancements. Despite being compatible with Swift 3, Swift 4 comes with several new and improved APIs. For instance, Swift 4 requires developers to use redesigned APIs for strings, dictionary, set, archival and serialization. Also, it enables developers to create multi-string literals using simple syntax. Swift 4 further introduces a new codable protocol that makes it easier for programmers to serialize and deserialize custom data types while writing complex code.

At the same time, Xcode 9 adds a number of new functionalities to the latest version of Swift. The new language features and improved APIs will persuade many developers to migrate their apps from Swift 3 to Swift 4. Apple keeps the Swift 3 to Swift 4 migration process simple and fast. Also, it allows developers to migrate their apps to Swift 4 smoothly by taking advantage of the migration tool provided by Xcode 9. But the developers still need to keep in mind some important factors when they migrate to Swift 4.

Important Factors a Developer Must Know to Migrate to Swift 4 Smoothly

Know the New Features and SDK Changes

When a developer decides to migrate to swift 4, it becomes essential for him to know the new language features and SDK changes. For instance, he has to adopt major SDK changes like converting string constants into Swift enumeration cases and moving global constants into static type properties. Likewise, he needs to understand various aspects of new and improved APIs for strings, dictionary, set, archival and serialization.

Choose the Right Language Mode

Swift 4 is fully compatible with Swift 3. But Swift 4 compiler supports two language modes – Swift 3.2 and Sift 4.0. A developer can opt for Swift 4.0 mode to take advantage of all new language features and APIs provided by the latest version of the programming language after migrating to Swift 4. On the other hand, Swift 3.2 mode makes the compiler accept the existing source code of an app built with earlier version of the compiler. Also, it will not update the APIs used by the app to maintain source code compatibility. But the mode still allows developers to avail the features of Swift 4.

Understand the Migration Process

As noted earlier, Swift 4 compiler supports two distinct language modes. A developer can easily accelerate the migration process by building the existing project in Swift 3.2. If the app is written in earlier versions of Swift, the developer has to rebuild the project in Swift 3.2 successfully to keep the migration process smooth. However, there are always chances that a developer has to manage a number of changes and address a number of issues while migrating the project to Swift 3.2 from earlier versions of the programming language.

Manage the Project under Source Control

Apple recommends developers to manage the project under source control when migrating to Swift 4. The source control makes it easier for the developer to monitor and review the changes being implemented by the Swift Migration Assistant. Also, he has option to discard certain changes that are unnecessary or irrelevant for the specific project. When the project is managed under source control, it becomes easier for the developer to restart the migration process without putting extra time and effort.

Take Advantage of Swift Migration Assistant

Xcode 9 makes it easier for developers to migrate to Swift 4 by providing the Swift Migration Assistant. A developer can access the Swift Migration Assistant as an item under the Issue Navigation. After invoking the migration tool, the developer has option to choose from a list of targets. He must choose a target that contains Swift code to start the migration process. Also, he has to follow a single migration workflow to migrate to Swift 4 smoothly. However, he still needs to address a number of issues immediately to process the targets properly and continue the migration process.

Implement Mechanical Changes Manually

The Swift Migration Assistant makes it easier for developers to upgrade their apps to Swift 4. But the developer still needs to resolve a number of changes and issues manually after completion of the migration process. The developer can easily identify the error or issues by filing a bug report through the Swift Migration Assistant. He must implement the required mechanical changes manually to keep the app’s functionality and performance intact after migrating to the latest version of Swift. After implementing the mechanical changes and resolving migration issues, the developer can rebuild the app in Swift 4 successfully.

On the whole, an iOS app developer can migrate to Swift 4 to take advantage of several new language features and improved APIs.  But he must understand the migration process clearly to migrate to Swift 4 seamlessly. Also, he needs to use the migration tool to migrate the app to Swift 4 without putting extra time and effort.

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