swift：如何将JSON传递给secondViewController

Question

我想将JSON数据传递给MainMenuPageViewController。

MainMenuPageViewController UILabel（UsernameLabel）

谢谢

图片1：

let jsonUserId: String = json["return"] as! String
if (jsonUserId != "0") {
    print("username and password correct")
    dispatch_async(dispatch_get_main_queue(), {
    let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let vc = storyboard.instantiateViewControllerWithIdentifier("MainMenuPageViewController")
    self.showViewController(vc, sender: self)
    //pass the jsonUserId to MainMenuPageViewController
    //MainMenuPageViewController has UILabel(UserIdLabel)
    })
}

如果输入错误的用户名和密码，系统将运行到第57行，但当我输入长字符串（a，A，@等）时，警报将会出错。但是，如果我输入镜头字符串（shing，herry，123等）应用程序可以显示警报消息。 另外，如果输入空格键和（！@＃$％^＆amp; *（）_ +）。它会出错。 你能帮我解决这个错误吗？谢谢。

Answer 1

只需在MainMenuPageViewController中声明变量，如

class MainMenuPageViewController: UIViewController {

var UserIdLabel = String()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}
}

和传递数据

  let jsonUserId: String = json["return"] as! String
 if (jsonUserId != "0") {
    print("username and password correct")
    dispatch_async(dispatch_get_main_queue(), {
        let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        if let vc = storyboard.instantiateViewControllerWithIdentifier("MainMenuPageViewController") as? MainMenuPageViewController {
           vc.UserIdLabel = jsonUserId
           self.showViewController(vc, sender: self)
        } 
     })
} 

Answer 2

您应该在MainMenuPageViewController中创建一个属性来存储用户ID，然后在viewDidLoad中将UsernameLabel文本设置为存储的属性。

var userID：String！ //在MainMenuPageViewController中定义它

然后在创建vc后，将userID属性设置为jsonUserID

if let vc = storyboard.instantiateViewControllerWithIdentifier("MainMenuPageViewController") as? MainMenuPageViewController { vc.userID = jsonUserId self.showViewController(vc, sender: self) } else { printf("The VC is not of the right type") }

override func viewDidLoad() { super.viewDidLoad() UsernameLabel.text = userID }