ios - 使用 Swift 1.2 从 Parse 检索对象

Question

我是网络、Xcode 和 Parse 的新手，我只是在关注 YouTube 教程，但由于某种原因代码无法运行。在这里。

func CallData(){
    var query : PFQuery = PFQuery(className: "QuestionsAndAnswers")
    query.getObjectInBackgroundWithId("DZfARcuav8"){

        (ObjectHolder : PFObject!, error : NSError!) -> Void in
        if (error == nil){
            self.Question = ObjectHolder["Question"] as! String
            self.Answers = ObjectHolder["Answers"] as! Array
            self.Answer = ObjectHoler["Answer"] as! String
            if (self.Answers.count > 0 ){
                self.QuestionLabel.text = self.Question
                self.Button1.setTitle(self.Answers[0], forState: UIControlState.Normal)
                self.Button1.setTitle(self.Answers[1], forState: UIControlState.Normal)
                self.Button1.setTitle(self.Answers[2], forState: UIControlState.Normal)
                self.Button1.setTitle(self.Answers[3], forState: UIControlState.Normal)
            }
        }
        else{
            NSlog("There is something wrong")
        }
    }
}

错误信息是

Cannot invoke 'getObjectInBackgroundWithId' with an argument of type '(String, (PFObject!,NSError!) -> Void)

Answer 1

您必须删除 PFObject!和 NSError! !标记闭包没有返回可选类型。试试下面的代码

 func CallData(){
    var query : PFQuery = PFQuery(className: "QuestionsAndAnswers")
    query.getObjectInBackgroundWithId("DZfARcuav8"){

        (ObjectHolder, error) -> Void in
        if (error == nil){
let object = ObjectHolder as [NSObject: AnyObject]
            self.Question = object["Question"] as String
            self.Answers = object["Answers"] as Array
            self.Answer = object["Answer"] as String
            if (self.Answers.count > 0 ){
                self.QuestionLabel.text = self.Question
                self.Button1.setTitle(self.Answers[0], forState: UIControlState.Normal)
                self.Button1.setTitle(self.Answers[1], forState: UIControlState.Normal)
                self.Button1.setTitle(self.Answers[2], forState: UIControlState.Normal)
                self.Button1.setTitle(self.Answers[3], forState: UIControlState.Normal)
            }
        }
        else{
            NSlog("There is something wrong")
        }
    }
}