CloudKit查询：在展开Optional值时意外发现nil

Question

我使用以下代码从CloudKit查询。但是，我得到了：

  

“在打开可选值时意外发现nil”

第publicDatabase!.perform行上的

错误：

print((currentuserID?.recordName)!)
let predicate = NSPredicate(format: "createdBy == %@", (currentuserID?.recordName)!)
let query = CKQuery(recordType: "Amigos", predicate: predicate)
print("Query record creators = to current user id")

publicDatabase!.perform(query, inZoneWith: nil, completionHandler: ({results, error in
    if (error != nil) {
        DispatchQueue.main.async {
            //self.notifyUser("Cloud Access Error",
            //message: error.localizedDescription)
            print("QUERY FAILED")
        }
    } else {
        if results!.count > 0 {

            print(results!.count)

            var record = results![0]

            print(record)

            DispatchQueue.main.async {
                print("moving user to updateLoc")
                let storyboard = UIStoryboard(name: "Main", bundle: nil)
                let vc = storyboard.instantiateViewController(withIdentifier: "updateLocation")
                self.present(vc, animated: true, completion: nil)

            }
        } else {
            DispatchQueue.main.async {
                //self.notifyUser("No Match Found",
                //message: "No record matching the address was found")
                print("no user currently")
                print("moving user to sign up page")
                let storyboard = UIStoryboard(name: "Main", bundle: nil)
                let vc = storyboard.instantiateViewController(withIdentifier: "signUp")
                self.present(vc, animated: true, completion: nil)
            }
        }
    }
}))

有谁知道为什么会这样？