在实际设备上的Glance中访问IBOutlet时，WatchKit“在解开可选值时意外发现nil”

Question

I have a Glance and some WKInterfaceLabel s. I use setHidden() on them in override func willActivate() depending on some conditions.

class GlanceController: WKInterfaceController {
  @IBOutlet weak var lName: WKInterfaceLabel!
  ...

override func willActivate() {
    // This method is called when watch view controller is about to be visible to user
    super.willActivate()
    if(conditions) {
        lName.setHidden(false)
    } else {
        lName.setHidden(true)
    }
  }
}

This works in simulator but on actual watch, I get fatal error: unexpectedly found nil while unwrapping an Optional value at lName.setHidden() .

Anyone saw this before?

Answer 1

As your "lName" is declared as explicitly unwrapped optional, it safer to access the variable following way -

   if let validLName = lName {
     if(conditions) {
        validLName.setHidden(false)
     } else {
        validLName.setHidden(true)
     }
   }
}

Answer 2

It appears that you are not allowed to use .setHidden() in Glance , at least for the current version of WatchKit .

I redesign my UI completely to use a single label and it works. Obviously it does not look as nice as I intend.

I understand the restriction but really hope there is more documentation to save the trouble. Just like I only found out I can't scroll in Glance after spending time designing the UI.