Resolving the unrecognized selector sent to instance Error in Swift Projects

Discover how to resolve the `unrecognized selector sent to instance` error in Swift projects caused by misconfigured IBAction connections. Read on for a step-by-step guide!
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Same code in one project works, fails in 2nd project: Thread 1: "-[Destini_iOS13.ViewController IBAction:]: unrecognized selector sent to instance"

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting the unrecognized selector sent to instance Error in Swift

As a new Swift programmer, encountering errors that seem cryptic can be particularly frustrating. One common issue is the unrecognized selector sent to instance error, which usually occurs when your code references something that doesn’t exist. If you have recently copied code from a project that works into a new project only to receive this error, fear not! We’re here to help you find the solution.

Understanding the Error

The error message you encountered, specifically:

[[See Video to Reveal this Text or Code Snippet]]

indicates that there’s a problem with the connection between your user interface (UI) elements in the storyboard and the corresponding functions in your code. This commonly happens when a button or UI element is linked to a method that either doesn’t exist or has been improperly linked.

What's Happening?

When you click the button in your app, the system tries to trigger a method that isn’t recognized. This can happen if:

The method has been deleted or renamed in the code.

The connection from the storyboard to the method is broken.

Step-by-Step Solution

To resolve the issue, you’ll need to ensure that your storyboard and code are correctly synchronized. Here’s how to do it:

1. Inspect the Button’s Connections

Right-click on the button that’s causing the issue. This will open a list of connections associated with that button.

2. Remove Existing Connections

Look for any items listed under Sent Events (especially the item for Touch Up Inside).

Remove all connections, as they may be outdated references that lead to the error.

3. Re-establish the Connection

Right-click and drag from the button to the ViewController code file. This action connects your UI to your code.

If the -IBAction function already exists: When you drag over it, you should see it highlight. Release the mouse to connect.

If you need to create a new -IBAction function: Drag to an empty line within the ViewController class, which will prompt Xcode to generate a new function for the button action.

Conclusion

By following these steps, you should successfully resolve the unrecognized selector sent to instance error in your Swift project. Maintaining proper connections between your storyboard and code is crucial for a smooth development experience, especially as you continue learning. Don’t hesitate to revisit these steps if you encounter similar issues in the future!

Final Thoughts

Swift is a powerful language, and with practice, these troubleshooting skills will become second nature. Happy coding!