How to Pass Data to the Previous View Controller of the Same Class in Swift

Описание: Learn how to effectively pass data back to a previous view controller of the same class in Swift using a simple and efficient approach.
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How to Pass Data to the Previous View Controller of the Same Class in Swift

Handling data flow between view controllers is a common challenge in mobile development, especially when you need to pass data back to the previous view controller. This can become particularly tricky when working with the same class of view controllers. In this post, we'll explore how you can achieve this in Swift, focusing on a scenario where you want to open a view controller from a table view, make some changes, and then pass data back to the previous instance of that view controller.

The Problem

You're working with a table view controller, and upon clicking a button in the navigation bar, you open another instance of the same view controller but with different settings based on certain flags. After making changes in this new instance, you want to close it and send the updated values back to the original instance so you can refresh the data displayed. Since you're dealing with the same class, you cannot use traditional delegation methods to relay that data back.

The Solution

You can resolve this problem using a simple approach by maintaining a reference to the original view controller from the new instance. Here’s how you can do it step-by-step:

Step 1: Create a Property to Hold the Reference

To begin, you’ll need to add a property in your view controller class to hold a reference to the previous instance of the view controller. Here's how you can define it:

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Step 2: Set the Property When Instantiating the New Controller

When you create a new instance of the view controller, you will set the creator property to the current instance (self). This step ensures that the new instance has a reference back to the original instance it came from. Here’s how to do that in your button action:

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Step 3: Update the Previous Instance's Property

In the new instance, when you want to pass back some updated data to the original view controller, simply access the creator property. Here, we will set the isContentFromPlaylist value to true before dismissing the new instance:

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Step 4: Reload the Table View

To ensure the original instance displays the updated information, you should reload the relevant data. This process should be done on the main thread. You can achieve that with the following code in your doneButtonPressed method:

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Conclusion

By following this method, you can easily pass data back to a previous view controller of the same class in Swift. This approach not only simplifies the flow of data between instances, but it also enhances the manageability of your application. Remember to always run UI updates on the main thread to avoid potential issues with the user interface.

If you encounter situations where you need to manage similar data flow in your Swift applications, try implementing this straightforward solution! Happy coding!