视图控制器在长时间延迟后被推入闭合

Question

在登录页面中，我使用闭包从帮助程序类接收 API 响应。收到回复后，我正在导航到另一个页面。该控件执行 pushViewController 行，但导航需要很长时间。是因为关闭吗？我该如何解决它？

class LandingView: UIViewController
{    
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    getStaticCountryAndStateList()
}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
// MARK: - Navigation
func getStaticCountryAndStateList()
{
    WebAPIHelper.getMethod(methodName: "/Common/GetStaticCountryAndStateList", success: {(response)->Void in
let signInObj = SignIn(nibName: (UIDevice.current.userInterfaceIdiom == .pad ? "SignIn" : "SignIn_iPhone"), bundle: nil)
            DispatchQueue.main.async
                {
                    self.navigationController?.pushViewController(signInObj, animated: true)
            }

    }, Failure: {
        (error)->Void in
        print("Error (error)")
    })
}
}

Answer 1

To push view controller fast in closure, you must access main queue. 
Below is code for accessing main queue in swift.
func getStaticCountryAndStateList()
{
    WebAPIHelper.getMethod(methodName: "/Common/GetStaticCountryAndStateList", success: {(response)->Void in
DispatchQueue.main.async {
 let signInObj = Payer(nibName: (UIDevice.current.userInterfaceIdiom == .pad ? "Payer" : "Payer_iPhone"), bundle: nil)
            self.navigationController?.pushViewController(signInObj, animated: true)
}
    }, Failure: {
        (error)->Void in
        print("Error (error)")
    })
}
}

Answer 2

在与您的 Web 请求不在同一线程上的主线程上推送视图。

Answer 3

始终在主线程中执行与 UI 相关内容的内容。

 dispatch_async(dispatch_get_main_queue(), ^{
        //update UI
 });

斯威夫特 3

DispatchQueue.main.async {
        // update ui
    }