具有可选功能实现的Swift @objc协议会导致生成错误

Question

I have the following protocol (which I'm using as a IBOutlet reference to the storyboard, so it must be with @objc).

/// This protocol implemented by views that contain a **main** 
    collection view.
@objc protocol CollectionInViewMethods {

      /// Notify the view that scrolling occurred.
      @objc optional func setSortingMenuFrame(newFrame: CGRect)
}

When I try to access the optional function using the swift syntax as follows:

self.cineamsView.setSortingMenuFrame?(newFrame: CGRect())

Which results with

Command failed due to signal: Segmentation fault: 11

While force unwrap build successfully (! instead of ?)

Is there any reason for that to happen? I saw that objective C does support optional functions in protocols, it seems to me like an Xcode bug...

Answer 1

I think you need to unwrap the function first see if it's not nil before calling it (only if you bridge it with a objective-c protocol)

This blog explains it: http://useyourloaf.com/blog/swift-optional-protocol-methods/