override 'shouldPerformSegueWithIdentifier' function throws error

I am trying to prevent all segues if a certain condition is not met. This is how I have approached this problem:

override func shouldPerformSegueWithIdentifier(identifier: String, sender: AnyObject?) -> Bool if condition == false print("Segue wont occur") return false else print("Segue will occur") return true

Though this solution seems to work for many people, I cannot compile, and I am thrown the error:

Method does not override any method from its superclass

The override function is located within the UIViewController superclass.

UIViewController

I am using Swift 4, and I have searched thoroughly for a solution. Any help would be appreciated.

“I am using Swift 4” no you aren’t. “and I have searched thoroughly for a solution” no you haven’t. That’s the problem. Look at the docs developer.apple.com/documentation/uikit/uiviewcontroller/… Copy and paste! It’s override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool

– matt
Sep 16 '18 at 13:11

override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool

An easy way to figure out yourself is to comment out the entire method, retype shouldPerf and use code completion.

– vadian
Sep 16 '18 at 13:14

@vadian thank you for that advice. I was stupid enough not to see that I had the ending wrong. Thank you for the time

– Caspar B
Sep 16 '18 at 13:24

@matt thank you for that answer. What do you mean when you say I am not using Swift 4?

– Caspar B
Sep 16 '18 at 13:26

@matt Okay, well I think we established that I mistakenly used a outdated function name. Doesn’t mean the rest of the code is Swift 1. I am programming in Swift 4.2, but a code snipped I used happened to be outdated and I didn’t realise. I think that’s where the confusion came from.

– Caspar B
Sep 16 '18 at 13:31

1 Answer
1

You seem to have gotten the method signature for shouldPerformSegue wrong.

shouldPerformSegue

override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool if condition == false print("Segue wont occur") return false else print("Segue will occur") return true

Thank you. I made a mistake and was stupid enough not to realise this.

– Caspar B
Sep 16 '18 at 13:22

When overriding methods, it is always better to let autocomplete do the job like @vadian has stated in his comment. No way of going wrong then.

– Rakesha Shastri
Sep 16 '18 at 13:22

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