Swift: overriding method with selector has incompatible type

Question

I have declared a class method in Objective-C:

+ (id) someFunction:(NSDictionary *)param;

When I subclass the class and override this method in Swift with this:

override class func someFunction(param : NSDictionary) -> AnyObject?

I get the error:

Overriding method with selector 'someFunction:' has incompatible type '(NSDictionary) -> AnyObject?'

How do I override the method correctly?

Answer 1

When I try to autocomplete that class function from somewhere else in Swift, Xcode tells me that param is an [NSObject: AnyObject]!, which makes the method declaration work:

override class func someFunction(param: [NSObject: AnyObject]!) -> AnyObject? {
    return "Foo"
}

This might be a compiler bug, since I'm pretty sure that's supposed to bridge properly to NSDictionary! (it seems to be bridging one way, but not the other, or something).