Swift : Define a closure compatible with Objective-C block

Question

I tried to declare a closure matching the following Objective-C block:

typedef void(^TyphoonDefinitionBlock)(TyphoonDefinition *definition);

like this:

var config: TyphoonDefinitionBlock = { (definition: TyphoonDefinition) in
    definition.injectProperty("quest", with: nil)
}

. . . and got the following error. (see image).

What's the correct way to do this?

Answer 1

You need to declare definition as an ImplicitlyUnwrappedOptional (TyphoonDefinition!) because in objective-C it is a pointer that can be nil.

Normal variables (and constants) in swift cannot be nil. They must contain a value.

Answer 2

I'm using typealias, taken from http://berzniz.com/post/87924122326/notes-from-coding-in-swift typealias resultBlock = (success: Bool, result: AnyObject!) -> Void