Ambiguous reference when using selectors

user_1373105 0
Viewed 528

Ready to use example to test in Playgrounds:

import Foundation

class Demo {

    let selector = #selector(someFunc(_:))

    func someFunc(_ word: String) {
        // Do something
    }

    func someFunc(_ number: Int) {
        // Do something
    }

}

I'm getting an Ambiguous use of 'someFunc' error.

I have tried this answer and getting something like:

let selector = #selector(someFunc(_:) as (String) -> Void)

But still getting the same result.

Any hints on how to solve this?

swift
2 Answers

Short answer: it can't be done.

Long explanation: when you want to use a #selector, the methods need to be exposed to Objective-C, so your code becomes:

@objc func someFunc(_ word: String) {
    // Do something
}

@objc func someFunc(_ number: Int) {
    // Do something
}

Thanks to the @objc annotation, they are now exposed to Objective-C and an compatible thunk is generated. Objective-C can use it to call the Swift methods.

In Objective-C we don't call a method directly but instead we try to send a message using objc_msgSend: the compiler is not able to understand that those method are different, since the generated signature is the same, so it won't compile. You will face the error:

Method 'someFunc' with Objective-C selector 'someFunc:' conflicts with previous declaration with the same Objective-C selector.

The only way to fix it is to have different signatures, changing one or both of them.

user_8138910

The selector is obviously ambiguous, neither methods have external parameter names. Remove the empty external parameters to solve this:

@objc func someFunc(word: String) {
    // Do something
}

@objc func someFunc(number: Int) {
    // Do something
}

After that, you should specify a selector with the parameter name:

#selector(someFunc(word:))

or

#selector(someFunc(number:))
user_31516750
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