How to Use canImport Analogue in Objective-C

Discover how to implement a `canImport` equivalent in Objective-C projects with flexible module importing solutions.
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This video is based on the question https://stackoverflow.com/q/52605302/ asked by the user 'Roman Podymov' ( https://stackoverflow.com/u/2229783/ ) and on the answer https://stackoverflow.com/a/64067747/ provided by the user 'spencer' ( https://stackoverflow.com/u/2637995/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving the canImport Equivalent in Objective-C

When working with Swift, the canImport condition introduced in Swift 4.1 has been a game-changer for developers. This feature allows you to check if a certain module can be imported in your project effortlessly. However, if you're developing in Objective-C, you might run into the challenge of achieving similar functionality. This guide will uncover how to implement an elegant solution for module importing in your Objective-C projects.

The Problem: Need for Flexible Module Imports

As Swift developers enjoy the convenience of canImport, Objective-C developers are left searching for workarounds. In an iOS project written in Objective-C, you might find yourself dealing with multiple targets where different modules are required. The ideal solution would allow you to check if a specific module can be imported just like in Swift.

You may have already relied on setting different "Other C Flags" for each target, but what if there was a more seamless approach? Let us explore how to tackle this issue with a practical solution.

The Solution: Using __has_include Preprocessor Directive

To accomplish this task in Objective-C, you can use the preprocessor directive __has_include. This directive checks if the specified header file is available for import, offering flexibility in handling modules. Here’s how to implement it:

Importing Your Module

You can start by checking for the existence of the module header file within your code. Here’s a step-by-step breakdown:

Check Module Availability: Use __has_include to verify if the module exists.

Import the Module: If the module is available, proceed with importing it.

Define a Macro: This macro can be used later in your code to conditionally compile different implementations based on whether the module is present.

Here’s an example of how to implement this:

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Utilizing the Check in Your Code

Once you have imported the module conditionally, you can use the defined macro to alter behavior in your code segments. This way, different paths can be executed depending on whether the module was successfully imported or not.

Here’s how you can use it within a method:

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Conclusion

In summary, while Swift offers the convenience of canImport, Objective-C developers are not left without options. Using the __has_include preprocessor directive allows for conditional imports based on the availability of module headers. This method provides a flexible and cleaner alternative to manually managing different flags across targets.

By following the steps outlined in this post, you can create a more robust and adaptable Objective-C codebase capable of handling module dependencies seamlessly. Happy coding!

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