Xcode 更改标签文本时的延迟响应（Swift）

我的问题是，当imageFound==false时，它会立即打印出“No Results！！！”，但标签文本更改大约需要15秒。我不知道为什么这是滞后，但我需要帮助尝试我=把它放在5秒或更少的范围内

代码如下

if let textFieldContent = textField.text{
        do {

            try WikiFaceRec.faceForPerson(textFieldContent, size: CGSize(width: 200, height: 250), completion: {(image:UIImage?, imageFound:Bool!) -> ()  in
                if imageFound == false{
                    self.faceImageView.alpha = 0
                    self.realLoadingLbl.text = "No Results Found. Check your spelling and try again."
                    print("NO RESULTS!!!!!")

                }
                if imageFound == true{
                   self.realLoadingLbl.alpha = 0
                    dispatch_async(dispatch_get_main_queue(), {() -> Void in
                        self.faceImageView.image = image

                        self.faceImageView.alpha = 1
                        WikiFaceRec.centerImageViewOnFace(self.faceImageView)
                    })

                }
            })
        } catch WikiFaceRec.WikiFaceError.CouldNotDownloadImage {
            print("Wikipedia not currently open")

        } catch {
            print("error")
            self.faceImageView.alpha = 0
            self.realLoadingLbl.text = "No Results Found. Check your spelling and try again."
            print("NO RESULTS")
        }
    }
    return true
}

下面的代码带有self.realLoadingLbl.text=“未找到结果。请检查拼写并重试。”这是需要稍加更改的部分。是的，再次“无结果！！！”会立即打印出来

if imageFound == false{
    self.faceImageView.alpha = 0
    self.realLoadingLbl.text = "No Results Found. Check your spelling and try again."
    print("NO RESULTS!!!!!")
}

---

在

dispatch\u async

方面，您必须处理与

true

类似的

imageFound==false

情况：

if !imageFound {
    dispatch_async(dispatch_get_main_queue()) {
        self.faceImageView.alpha = 0
        self.realLoadingLbl.text = "No Results Found. Check your spelling and try again."
        print("NO RESULTS!!!!!")
        self.faceImageView.alpha = 0                      
    }
}

---

在

dispatch\u async

方面，您必须处理与

true

类似的

imageFound==false

情况：

if !imageFound {
    dispatch_async(dispatch_get_main_queue()) {
        self.faceImageView.alpha = 0
        self.realLoadingLbl.text = "No Results Found. Check your spelling and try again."
        print("NO RESULTS!!!!!")
        self.faceImageView.alpha = 0                      
    }
}