我刚接触网络，Xcode和Parse，并且我只是遵循YouTube教程，但由于某些原因代码无法运行。这里是。使用Swift从Parse中检索对象1.2
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")
}
}
}
错误消息说
不能援引 'getObjectInBackgroundWithId' 类型的参数“（字符串，（PFObject，NSError）！ - >无效）
===========解决方案如下：
你必须删除PFObject！和NSError！ ！标记闭包没有返回一个可选类型。尝试follwing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")
}
}
}