Firebase setValue无法在IOS 10，Swift 3中运行(Firebase setValue not working in IOS 10, Swift 3)

 当我尝试将评论保存到Firebase时，我的应用程序崩溃了。 此代码在Xcode 8更新之前完美运行： 
 
    func saveNewComment(){

    //get date
    let date = Date()
    let calendar = Calendar.current
    let components = (calendar as NSCalendar).components([.day,.month,.year], from: date)

    let year = components.year
    let month = components.month
    let day = components.day

    //format month
    let dateFormatter: DateFormatter = DateFormatter()
    let months = dateFormatter.shortMonthSymbols
    let monthSymbol = months?[month!-1]
    let todaysDate = "\(day) \(monthSymbol),\(year)"

    //trim comment
    let comment = textView.text
    let trimmedComment = comment?.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)

    //save new comment
    let commentRef = ref.child("Stores").child(getRef!).child("CommentArray").childByAutoId()

    commentRef.setValue([

        "Comment": trimmedComment,
        "Date": todaysDate

    ])

    self.delegate?.commentSubmitted(true)//delegate
    self.dismiss(animated: true, completion: nil)//dismiss view

}
 
 显然，错误是当我尝试使用“setValue”来设置这些键值对时。 任何想法为什么会发生这种情况？ 
 
 提前致谢。 

My app is crashing when I try to save a comment to Firebase. This code was working perfectly before the Xcode 8 update:
 
    func saveNewComment(){

    //get date
    let date = Date()
    let calendar = Calendar.current
    let components = (calendar as NSCalendar).components([.day,.month,.year], from: date)

    let year = components.year
    let month = components.month
    let day = components.day

    //format month
    let dateFormatter: DateFormatter = DateFormatter()
    let months = dateFormatter.shortMonthSymbols
    let monthSymbol = months?[month!-1]
    let todaysDate = "\(day) \(monthSymbol),\(year)"

    //trim comment
    let comment = textView.text
    let trimmedComment = comment?.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)

    //save new comment
    let commentRef = ref.child("Stores").child(getRef!).child("CommentArray").childByAutoId()

    commentRef.setValue([

        "Comment": trimmedComment,
        "Date": todaysDate

    ])

    self.delegate?.commentSubmitted(true)//delegate
    self.dismiss(animated: true, completion: nil)//dismiss view

}
 
Apparently the error is when i try to use "setValue" to set those key value pairs. Any ideas why is this happening? 
 
Thanks in advance.

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