swift - How to use optional binding in switch statement in prepare(segue:) -

in swift can use cool feature of switch statement in prepare(segue:) create cases based on type of destination view controller:

example:

override func prepare(for segue: uistoryboardsegue, sender: any?) {     switch segue.destination {      case let detailviewcontroller detailviewcontroller:       detailviewcontroller.title = "detailviewcontroller"     }     case let otherviewcontroller otherviewcontroller:       otherviewcontroller.title = "otherviewcontroller"     } } 

however, if segue triggered split view controller, destination navigation controller, , want switch on class of navigation controller's top view controller?

i want this:

case let nav uinavigationcontroller,      let detailviewcontroller = nav.topviewcontroller as? detailviewcontroller:     //case code goes here 

where have same construct use in multiple part if let optional binding.

that doesn't work. instead, have rather painful construct this:

case let nav uinavigationcontroller   nav.topviewcontroller detailviewcontroller:   guard let detailviewcontroller = nav.topviewcontroller as? detailviewcontroller     else {       break   }   detailviewcontroller.title = "detailviewcontroller" 

that works, seems needlessly verbose, , obscures intent. there way use multi-part optional binding in case of switch statment in swift 3?

i don't think there way switch , case, can closer looking if , case (update: hamish pointed out, case isn't needed scenario) or normal if let:

override func prepare(for segue: uistoryboardsegue, sender: any?) {      if let nav = segue.destination as? uinavigationcontroller,          let detailviewcontroller = nav.topviewcontroller as? detailviewcontroller {         detailviewcontroller.title = "detailviewcontroller"     }      if let otherviewcontroller? = segue.destination as? otherviewcontroller {         otherviewcontroller.title = "otherviewcontroller"     } } 

since switch statement in example isn't going ever verified compiler handling cases (because need create default case), there no added benefit using switch instead of if let