ios - 错误检查无法正常用于解析查询

Question

所以我在解析服务器中有一个名为“classes”的类，我试图在我的程序中实现一个错误检查查询。 Xcode 项目构建正确，但是，当我尝试错误检查我的查询以搜索类时，程序总是说搜索成功，即使该类类型的对象不在查询中。这是代码:

  @IBAction func searchClass(_ sender: Any) {

    let query = PFQuery(className: "Classes")
    query.findObjectsInBackground { (success, error) in
        if error != nil{
            self.createAlert(title: "Error", message: "Cannot find class")
        } else {
            self.createAlert(
                title: "Success", message: "Found the query")
            self.classSuccess = true
            self.flipCardButton.alpha = 0
            UIView.transition(from: self.classQuery, to: self.classRate, duration: 0.5, options: .transitionFlipFromRight)
            self.goBackButton.alpha = 1
        }
    }

这是我应用程序中的搜索按钮:

Screenshot of Simulator

使解析查询检查始终打印成功可能会出现什么问题？

Answer 1

我认为您在查询中遗漏了成功语句。

let query = PFQuery(className: "Classes")
query.findObjectsInBackground { (success, error) in
    if error != nil{
        print(error ?? "") 
        self.createAlert(title: "Error", message: "Cannot find class")
    } 

    if success {
        self.createAlert(
            title: "Success", message: "Found the query")
        self.classSuccess = true
        self.flipCardButton.alpha = 0
        UIView.transition(from: self.classQuery, to: self.classRate, duration: 0.5, options: .transitionFlipFromRight)
        self.goBackButton.alpha = 1

    } else {
       self.createAlert(title: "Error", message: "Cannot find class")
    }
}