如何在 iOS Swift 3 中以编程方式推送和呈现给 UIViewController 而无需 segue答案

【问题标题】：How to push and present to UIViewController programmatically without segue in iOS Swift 3如何在 iOS Swift 3 中以编程方式推送和呈现给 UIViewController 而无需 segue
【发布时间】：2017-02-17 04:22:07
【问题描述】：

我正在使用此代码在 iOS 中以编程方式推送 SHOW 和 MODALLY > 目标 C。
现在想了解 Swift 3。

NewsDetailsViewController *vc =  instantiateViewControllerWithIdentifier:@"NewsDetailsVCID"];
vc.newsObj = newsObj;
//--this(SHOW)
[self.navigationController pushViewController:vc animated:YES];  
//-- or this(MODAL)
[self presentViewController:vc animated:YES completion:nil];

【问题讨论】：

标签： ios swift xcode swift3 uiviewcontroller

【解决方案1】：

推送

喜欢

let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("NewsDetailsVCID") as NewsDetailsViewController 
 vc.newsObj = newsObj
 navigationController?.pushViewController(vc,
 animated: true)

或者更安全

  if let viewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "NewsDetailsVCID") as? NewsDetailsViewController {
        viewController.newsObj = newsObj
        if let navigator = navigationController {
            navigator.pushViewController(viewController, animated: true)
        }
    }

呈现

   let storyboard = UIStoryboard(name: "Main", bundle: nil)
   let vc = self.storyboard?.instantiateViewControllerWithIdentifier("NewsDetailsVCID") as! NewsDetailsViewController
      vc.newsObj = newsObj
           present(vc!, animated: true, completion: nil)

或者更安全

   if let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "NewsDetailsVCID") as? NewsDetailsViewController
     {

     vc.newsObj = newsObj
    present(vc, animated: true, completion: nil)
    }

【讨论】：

你能解释一下or safer这里的部分吗，+1。
@vaibhav “或更安全”是指在实例化视图控制器时处理潜在的可选“nil”情况。 "if let" 是在 swift 中处理可选 nil 的经典方式。
如果我在情节提要中没有任何视图控制器，但我正在以编程方式进行操作，那么我应该怎么做才能调用或声明视图控制器的 ID
@iOSDeveloper- 如果它在程序上你可以直接调用 VC
为什么需要安全地打开它？它们都导致发生同样的事情 - 如果 navigationController 存在，它会推送视图控制器，否则什么也不会发生。

【解决方案2】：

以优雅的方式。

创建导航协议：

protocol Navigatable {
    /// Storyboard name where this view controller exists.
    static var storyboardName: String { get }


    /// Storyboard Id of this view controller.
    static var storyboardId: String { get }

    /// Returns a new instance created from Storyboard identifiers.
    static func instantiateFromStoryboard() -> Self
}

创建一个默认的实例化控制器实现：

/**
 Extension of Navigatable protocol with default implementations.
 */
extension Navigatable {
    static func instantiateFromStoryboard() -> Self {
        let storyboard = UIStoryboard(name: self.storyboardName, bundle: nil)
        guard
            let viewController = storyboard
                .instantiateViewController(withIdentifier: self.storyboardId) as? Self else {
                    fatalError("Cannot instantiate the controller.")
        }

        return viewController
    }
}

扩展UIViewController 以推送视图控制器：

extension UIViewController {
    /**
     Pushes a view controller of the provided type.

     - Parameter viewControllerType: Type of view controller to push.
     - Parameter completion: Function to be executed on completion.
     Contains the view controller that was pushed when successful and nil otherwise.
     */
    func pushViewControllerOfType<T: Navigatable>(viewControllerType: T.Type, completion: (T) -> Void) {
        let viewController = T.instantiateFromStoryboard()
        if let vc = viewController as? UIViewController {
            self.pushViewController(vc, animated: true)
        }
        completion(viewController)
    }


    /**
     Pushes a view controller of the provided type.

     - Parameter viewControllerType: Type of view controller to push.
     */
    func pushViewControllerOfType<T: Navigatable>(viewControllerType: T.Type) {
        self.pushViewControllerOfType(viewControllerType: viewControllerType) { _ in }
    }
}

然后您可以将Navigatable 协议用于特定的视图控制器。

class MySuperViewController {
   override func viewDidLoad() {
      ...
   }
   // ...
}
extension MySuperViewController: Navigatable {
    static var storyboardName: String {
        return "Main"
    }

    static var storyboardId: String {
        return "MySuperViewControllerId" // From your story board name Main
    }
}

// Instantiate your controller
let vc = MySuperViewController.instantiateFromStoryboard()

// Or
//
// Push your view controller

// testViewController.swift

self.pushViewControllerOfType(viewControllerType: MySuperViewController)

【讨论】：

【解决方案3】：

//Create object of view controller 
let obj = self.storyboard?.instantiateViewController(withIdentifier: "ViewControllerIdentifier”) as! ViewControllerName

//Push Controller
self.navigationController?.pushViewController(obj, animated: true)

//Present Controller
self.navigationController?.present(obj, animated: true, completion: nil)

【讨论】：