How to Switch Your Apps from Objective-C to Swift

iOS

Many existing iOS applications need to change in Swift code thanks to myriads of benefits the Swift brings with it. Many iOS developers are wondering how to convert apps from Objective-C code to Swift, so this post is giving you useful tips and easy steps to go ahead in the conversion process.

Introduction:

When Apple Inc. has released the first iPhone SDK in 2007 and invited third-party developers to create iPhone apps, it has declared Objective-C as official iOS programming language supporting X-code as development tool & IDE. After seven years, in 2014 again iOS platform has declared Swift as a next-generation programming language in addition to Objective-C.

Swift comes with myriads of advantages over Objective-C and completely befitting for contemporary needs. Therefore, Apple has avoided upgrading Objective-C and created Swift from scratch. Thus, seasoned iOS developer avoid converting Objective-C code into Swift code and write an app in the Swift code from scratch.

However, some apps are of a big scale and writing from scratch in Swift proves costly affairs, so developers prefer to use converting tools available in the X-code or from third-party service providers and manage things tactfully.

Objective-C to Swift Converter

Apple offers modern Objective-C converter in X-code, which helps developers to do following important things during conversion.
  • Implementing Enum Macros
  • Changing ID to InstanceType
  • Assists in updating @proprty syntax

We should keep one thing in mind that converter helps us only in detection and implementation of mechanics of potential changes. It will never represent the semantics of the code. It means iOS developers have to go manually for alterations and improve the quality of resulting Swift code.

To use converter in X-code Edit -> Convert -> To Modern Objective-C Syntax
Or
Edit -> Refactor -> Change To Modern Objective-C Syntax To convert a full Objective-C app to Swift, use Swiftify.
 

Tips While Using Objective-C to Swift Converter

Before giving you a step-by-step guide to convert the code, I would like to give you following tips.

Attend One Class at a Time

The program paradigms of both iOS languages are different and can create issues if we are going to use tools, which are converting code line-by-line. Therefore, it is advisable to covert one class at a time.

Remember that unlike Objective-C, Swift doesn’t have subclasses. Therefore, you will end up with two different types of files in app code document, (.h) type and (.m) type.

  • (.h) type contains a @interface section
  • (.m) type contains a @implementation section
Since (.m) file imports (.h) file whenever the need arises to refer to a class and eliminate the creation of header file.

Creating a Bridging Header

Once you add an Objective-C file into Swift target or vice verso, you will have chances to develop a bridging header file. Thus, when you import (.h) file into bridging header, it becomes visible to Swift.

Accomplish Nil Check

You get a zero value in return wherever a message is sent to nil object in Objective-C programming. If you want to avoid it, you must perform nil checks as per need.

Get Wrapped Value

You can substitute the Optional with String in the Swift because you can get syntactic sugar for starting types optional. When you use two methods including Optional Chaining and Forced Wrapping, you receive wrapped value from the elective container in two conditions:

  1. If conditional statement obtains a value when it exists
  2. If the conditional statement is not nil

Use Tuples

Besides Optionals, Apple has new development language define as Tuples. Its aim is different grouping values into one compound value, which is a better tool to create a model at a place.

Conversion Process

Let’s check it step-by-step.
  1. Select a pair of (.h) and (.m) files you want to convert
  2. Search #import “MyViewController.h” across the code document and remove it
  3. In all .m files, you need to replace #import “[filename].h” instances with #import “[MyProject]-Swift.h”
  4. In all the .h files, replace @class [filename] with #import “[filename].h”
  5. Now, transform Objective-C files to Swift using Swiftify Xcode Extension
  6. Replace (.h) and (.m) files with converted (.swift) files
  7. Now, it is time to fix the conversion error, and Swiftify extension can help you in this regard
  8. Now, you can build and run the project smoothly
  9. If you have chosen to convert the entire project, you can transform AppDelegate class now

Conclusion:

After an overview of the entire conversion process, you may have decided that you should have an expert team of iOS developers who used to do the same and converted several projects successfully. In due course, a team of iOS app developers at SysBunny may prove a right choice for you even you want to create your Objective-C app from scratch in Swift code.

Would you like to begin a thread of conversations with us?
Hemant Parmar is a veteran mobile app consultant. He is co-founder of the company. Thanks to his prolonged exposure to mobile application development projects for myriads of niches and industries, he is capable of providing high-end mobile app development consultancy. He is devoted to providing honest and transparent consultancy services for clienteles looking for righteous guidance to augment their niche services/products using the latest mobile technologies.

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