JSExportAs Workaround in Swift (simplified code example)

gistfile1.swift

public typealias myFunctionDefAlias = (@objc_block (String, String, NSNumber) -> Void)

@objc
public protocol MyJSExportProtocol: JSExport {
    // JSExportAs alternative in Swift via closure
    var myFunction:myFunctionDefAlias? {get}
}

@objc
public class MyJSExportClass: NSObject, MyJSExportProtocol {
    public var myFunction:myFunctionDefAlias?
    public func init() {
    	self.myFunction = { [unowned self] (foo:String, bar:String, baz: NSNumber) in
                self.myFunctionImpl(foo, bar: bar, baz: baz)
            }
    }
    
    public func myFunctionImpl(foo: String, bar: String, baz: Bool) {
    }
}

I'm getting the error: @objc_block is an unknown attribute

Wish a workaround wasn't needed for JSExportAs.