CODEWITHSUNDEEP
swift4
user2924482
user2924482

Reputation: 9120

Swift: Optional variable in function signature showing error Method cannot be marked @objc because the type

I'm working in swift framework but I need to support ObjC. But I have a function like this:

@objc public func doingSomething(thing:String?,time:Int?)->String{

    return result
}

But I'm getting the following error:

Method cannot be marked @objc because the type of the parameter 2 cannot be represented in Objective-C

Any of you knows a work around this error?, or how can I fix this error?

I'll really appreciate your help.

Upvotes: 1

Views: 692

Answers (1)

Charles Srstka
Charles Srstka

Reputation: 17040

The problem is that integers are a primitive type in Objective-C, so the language is not capable of assigning nil to an integer-typed variable. Therefore, you cannot have Int? in the signature of a method that is exposed to Objective-C.

As a workaround, you can either make the parameter an Int and define a sentinel value to represent a nil value (NSNotFound is an example found in the various "indexOf" methods in the frameworks; 0 may work in some cases), or else you can type the parameter as an NSNumber? since NSNumber is an object type and thus can be nil.

Upvotes: 5

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