swift - 解析和 Swift getObjectInBackgroundWithId

Question

我有以下代码，但仍然显示错误

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

我试图让 Swift 随机选择 Parse 中的一行，以便每次都是随机的。

func CallData(){
    GetRandomObjectID()
    if(ObjectIDsPublicArray.count > 0){
        var query : PFQuery = PFQuery(className: "QuestionsandAnswers")
        query.getObjectInBackgroundWithId(ObjectIDsPublicArray[RandomID]){
        (ObjectHolder : PFObject!, error : NSError!) -> Void in
            if (error == nil){
                self.Questions = ObjectHolder["Questions"] as! String!
                self.Answers = ObjectHolder["Answers"] as! Array!
                self.Answer = ObjectHolder["Answer"] as! String!
            }

Answer 1

看起来 Swift 在强制 PFObject 存在方面存在问题。尝试将对象和错误设置为可选:

(ObjectHolder: PFObject?, error: NSError?) -> Void in