Errors while using shouldPerformSegue(withIdentifier, sender) method in swift4

Question

What I\'m trying to do:

• checking a condition, if the condition is true, perform segue as normal. If condition is false, call the shouldPerformSegue method and retu

Answer 1

First of all, you’re attempting to provide a closure as the third parameter to the method, which doesn’t take three parameters, doesn’t take a closure as a parameter at all and this method shouldn’t be called by your code at all.

Second, implement some sort of Boolean flag ‘isSegueActive’ which would be set to ‘false’ or ‘true’ depending on the condition in the related button action.

Third, override ‘shouldPerformSegue’ in your view controller and make it return the value of ‘isSegueActive’.

That way when performing the segue, your view controller will call ‘shouldPerformSegue’ to know whether a segue should be performed.

Answer 2

If you want to perform logic to decide if a segue should be "performed" or not, you need to override shouldPerformSegue. This will allow the OS to (1) kick off things properly and (2) for you to be able to decide if the segue gets done.

override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {
    if [criteria met to perform segue] {
        return true
    } else {
        return false
    }
}