ios - 在 viewDidLoad 之前执行一个函数

Question

此 View 将提出一组问题。这些问题将从 api 中读取。我有两种方法可以在最后一个 View 中加载它们，或者在当前 View 中但在 viewDidLoad 方法之前加载它们。我尝试了 viewWillAppear 但效果不佳。我该怎么做？

编辑:

这是从 api 读取数据的函数:

func readData(id: String, userCompletionHandler: @escaping ([String], Error?) -> Void){
            let request = NSMutableURLRequest(url: NSURL(string: "http://adminsapi.somee.com/Api/Test/?id=\(id)")! as URL, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 10.0)
            request.httpMethod = "GET"

            var questionArr = [String]()
            let session = URLSession.shared
            let dataTask = session.dataTask(with: request as URLRequest, completionHandler: {
                (data, response, error) in
                if response != nil {
                    //print("Response: \(response!)")
                }
                if let data = data {
                    do{
                        self.questionObject = try JSONDecoder().decode([Questions].self, from: data)
                        for question in self.questionObject{
                            questionArr.append(question.question)
                        }
                        userCompletionHandler(questionArr, nil)
                    } catch{
                        print("Error in retrieving data: \(error)")
                    }
                }
                else{
                    print("Error: \(String(describing: error))")
                }
                })
            dataTask.resume()
        }

这是我导航到下一个 View Controller 的地方:

func moveToNextVC(finalString: String){
        let VC1 = self.storyboard?.instantiateViewController(withIdentifier: "QuestionsTableViewController") as? QuestionsTableViewController
        if finalString.lowercased().contains("abdominal distention"){
            readData(id: "1", userCompletionHandler: { data, error in
                VC1?.questions = data
            })
            self.present(VC1!, animated: true, completion: nil)
        }
    }

The problem is when I print the questions array in "QuestionsTableViewController" it is always empty

Answer 1

按从左到右的顺序

loadView -> viewDidLoad -> viewWillAppear

在 loadView 中也没有足够的时间来做这件事，你需要在之前的vc中加载api然后显示需要的 1 ，或者在viewDidLoad里面调用