Ios 如何将数据从一个viewcontroller传递到另一个viewcontroller，该viewcontroller是json格式的，需要在tableview中设置？

这是我的密码：

public func getMethod() -> Array<Any>{
    var array = [Any]()
    let session = URLSession.shared
    let aURL = URL(string: baseUrl+month)!
    var request = URLRequest(url: aURL)
    request.setValue("application/json", forHTTPHeaderField: "Accept")
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    request.setValue("Bearer \(UserDefaults.standard.string(forKey: Actoken)!)", forHTTPHeaderField: "Authorization")
    let task = session.dataTask(with: request, completionHandler: {(data, response, error) in
        do {
            let json = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.allowFragments)
            array = [json]
            print(array)
            print(json)
        } catch {
            print("Could not serialise")
        }

    })
    print(array)
    task.resume()

    return array
}

但当我尝试在另一个视图控制器中返回时，它返回的是null值。 如果不是这样的话，我该怎么做呢。

---

我需要将派生的json插入到表视图中。

对于任何异步操作，都应该使用

completion

，因此您的代码应该如下所示：

class classA {

public func getMethod(completion: @escaping (_ resultArray: [Any])->()) {
        var array = [Any]()
        let session = URLSession.shared
        let aURL = URL(string: baseUrl+month)!
        var request = URLRequest(url: aURL)
        request.setValue("application/json", forHTTPHeaderField: "Accept")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        request.setValue("Bearer \(UserDefaults.standard.string(forKey: Actoken)!)", forHTTPHeaderField: "Authorization")
        let task = session.dataTask(with: request, completionHandler: {(data, response, error) in
            do {
                let json = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.allowFragments)
                array = [json]
                completion(array)
            }
            catch {
                print("Could not serialise")
            }
        })
        task.resume()
    }
}

//打电话的人应该是

let yourClass = classA()
yourClass.getMethod { [weak self] (resultArr) in
    DispatchQueue.main.async {
        let classB = ClassB()
        classB.resultArray = resultArr
        self?.navigationController.pushViewController(classB, animated: true)
        }
    }

---

一旦使用结果数组将其推送到classB，您就可以解析JSON响应并填充到tableView中。

将闭包传递到getMethod中，该方法将在收到响应时执行。在闭包内部，使用json更新tableview的数据源，然后重新加载数据

public func getMethod(completion: (yourCustomType)->() ) {

    ...

    let task = session.dataTask(with: request, 
                   completionHandler: {(data, response, error) in

        if let data = data {
            do {
                let json = try JSONDecoder.decode(yourCustomType.self, data)
                completion(json)
            }catch {
                    ...
            }
        }

   })

   task.resume()
}

getMethod() { (responseData: YourCustomType) in
    tableviewDatasource = responseData
    DispatchQueue.main.async{ 
        self.tableview.reloadData
    }
}

---

异步编程不是这样工作的

您正在进行异步调用（

session.dataTask

调用），并希望同步返回结果。调用函数可能在网络调用完成之前读取结果。您应该使用闭包（完成块）

下面是一些演示异步模型的简单代码：

import UIKit
import PlaygroundSupport

PlaygroundPage.current.needsIndefiniteExecution = true

let Actoken = "SOMETHING"

public func getMethod(baseUrl:String, month:String, completion:@escaping (Array<Any>?)->()){

    var array = [Any]()
    let session = URLSession.shared
    guard let aURL = URL(string: baseUrl+month) else {
        print("invalid url")
        completion(nil)
        return
    }
    var request = URLRequest(url: aURL)
    request.setValue("application/json", forHTTPHeaderField: "Accept")
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    let task = session.dataTask(with: request, completionHandler: {(data, response, error) in
        do {
            if let data = data {
                let json = try JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.allowFragments)
                array = [json]
                completion(array)
            } else {
                completion(nil)
            }
        }
        catch {
            print("Could not serialise")
            completion(nil)
        }
    })
    task.resume()
}

// here's how you call it from the view controller
getMethod(baseUrl: "https://mobilesecurity.win/sample.json", month: "") { array in
    if let array = array {
        print(array)
    } else {
        print("array was nil")
    }
}

导入UIKit
导入PlaygroundSupport
PlaygroundPage.current.NeedsDefiniteExecution=true
让Actoken=“某物”
public func getMethod（baseUrl:String，month:String，completion:@escaping（Array？）->（））{
变量数组=[Any]（）
让session=URLSession.shared
guard let aURL=URL（字符串：baseUrl+month）else{
打印（“无效url”）
完成（无）
回来
}
var-request=URLRequest（url:aURL）
request.setValue（“application/json”，forHTTPHeaderField:“Accept”）
request.setValue（“application/json”，forHTTPHeaderField:“Content Type”）
让task=session.dataTask（带：request，completionHandler:{（数据，响应，错误））在
做{
如果let data=data{
让json=try JSONSerialization.jsonObject（with:data，options:JSONSerialization.ReadingOptions.allowFragments）
数组=[json]
完成（数组）
}否则{
完成（无）
}
}
抓住{
打印（“无法序列化”）
完成（无）
}
})
task.resume（）
}
//下面是如何从视图控制器调用它
getMethod（baseUrl:）https://mobilesecurity.win/sample.json，月份：）{中的数组
如果让数组=数组{
打印（数组）
}否则{
打印（“数组为零”）
}
}

import UIKit
import PlaygroundSupport

PlaygroundPage.current.needsIndefiniteExecution = true

let Actoken = "SOMETHING"

public func getMethod(baseUrl:String, month:String, completion:@escaping (Array<Any>?)->()){

    var array = [Any]()
    let session = URLSession.shared
    guard let aURL = URL(string: baseUrl+month) else {
        print("invalid url")
        completion(nil)
        return
    }
    var request = URLRequest(url: aURL)
    request.setValue("application/json", forHTTPHeaderField: "Accept")
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    let task = session.dataTask(with: request, completionHandler: {(data, response, error) in
        do {
            if let data = data {
                let json = try JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.allowFragments)
                array = [json]
                completion(array)
            } else {
                completion(nil)
            }
        }
        catch {
            print("Could not serialise")
            completion(nil)
        }
    })
    task.resume()
}

// here's how you call it from the view controller
getMethod(baseUrl: "https://mobilesecurity.win/sample.json", month: "") { array in
    if let array = array {
        print(array)
    } else {
        print("array was nil")
    }
}