Solving the Common Value of type 'UIViewController' has no member... Error in Swift Extensions

Описание: Learn how to effectively handle the `Value of type 'UIViewController' has no member...` error when using `inout` parameters in Swift extensions, particularly during the implementation of loading views.
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This video is based on the question https://stackoverflow.com/q/63951860/ asked by the user 'biggreentree' ( https://stackoverflow.com/u/4846391/ ) and on the answer https://stackoverflow.com/a/63952469/ provided by the user 'Sweeper' ( https://stackoverflow.com/u/5133585/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Tackling the Value of type 'UIViewController' has no member... Error in Swift Extensions

When developing iOS applications in Swift, it's not uncommon to encounter various errors that can slow down your progress. One such error is the dreaded Value of type 'UIViewController' has no member... when trying to use a function with an inout parameter inside an extension.

If you've found yourself stuck on this particular issue, this post will walk you through understanding the error and provide a clear solution to effectively manage loading views in your UIViewControllers.

Understanding the Problem

The error typically arises when you're trying to access a property or method inside an extension that isn't available in the context you're working with. In your case, this error surfaced when you attempted to use self.containerForLoading within a closure that captures an inout parameter. This situation can often lead to confusion, especially when dealing with closures and view visibility.

Common Issues

Accessing Properties: Within an extension, you may not have direct access to properties of the class unless they are defined at that scope.

Closure Capture: Swift requires certain considerations when capturing variables inside closures, particularly with inout parameters.

Step-by-Step Solution

To resolve this issue, we can refactor your showLoadingView and removeLoading functions to manage loading views without relying on inout parameters. Here’s how to implement a better approach:

Refactoring Your Code

Use Local Variables: Instead of passing an inout parameter for the loading view, maintain it as a local variable within the function. This way, you sidestep the issue of trying to access it through self.

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Updating Calls: When you wish to show or remove the loading view, simply call these methods from your UIViewController without needing to deal with inout parameters:

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Why This Approach Works

Simplicity: By eliminating the need for inout parameters, your code becomes cleaner and easier to read.

Tagging Mechanism: Using the tag allows you to uniquely identify the loading view without needing to pass it around. This pattern is commonly used in iOS development for dynamically created views.

Avoiding Complexity: It reduces the potential for errors caused by mismanaging state and properties across extensions and closures.

Conclusion

Navigating errors in Swift, especially when dealing with extensions and closures, can be tricky. By understanding how to manage state and references properly, you can eliminate common pitfalls such as the Value of type 'UIViewController' has no member... error. The solution provided not only addresses the issue but also encourages better practices in Swift development.

Happy coding, and may your apps run smoothly!