导航到同一屏幕，但从两个不同的ViewController

Question

所以我有3个VC

ViewController1,ViewController2,ViewController3

现在，我在ViewController2和ViewController3都有一个按钮，通过点击它们导航到ViewController1 ，从vc2导航和从vc3导航时，UI会有微小的变化。

所以我想知道处理这个问题的最佳实践。 我怎么知道从哪个vc到达VC1 ？？

Answer 1

您可以使用标志或枚举。 我建议对于enum bcz，将来有时您可能会从多个控制器推送到VC​​1。 使用枚举始终很方便。

1. 带标志

class ViewController1: UIViewController {
    // default value is false bcz if you forgot to assign this value then atleast your app won't crash.
    var isFromVC2 : Bool = false
        :
        :
}

• 使用->在您的VC1文件中

   if isFromVC2 { // Do code for VC2 } else { // Do code for VC3 } 

2. 与枚举

enum ComingFrom {
    case VC3
    case VC2
}

class ViewController: UIViewController {
    // default value VC2
    var whichController : ComingFrom = .VC2
      :
      :
}

• 采用

   switch whichController { case .VC2: // for vc2 Code case .VC3: // for VC3 Code default: // If you forget to assign `whichController` or there will be new condition in future } 

编辑：如何分配whichController

let vc = self.storyboard?.instantiateViewController(withIdentifier: "ViewController1") as! ViewController1
vc.whichController = .VC2
self.navigationController?.pushViewController(vc, animated: true)

• 为了更清晰

Answer 2

在VC1中，创建一个变量作为vcNames。

class VC1: UIViewController {
        var vcNames = ""
 override func viewDidLoad() {
        super.viewDidLoad()
        //Check your vc's with vcNames.
   }
}

现在，当从VC2或VC3推送到vc1时，只需将当前的vc名称传递给创建的变量即可。

 let tempVC1 = UIStoryboard.init(name: "Main", bundle: Bundle.main).instantiateViewController(withIdentifier: "VC1") as? VC1
 tempVC1?.vcNames =  "vc2" //Assign your vc name here
 self.navigationController?.pushViewController(tempVC1!, animated: true)

Answer 3

添加唯一的Bool变量，以便您可以了解该控制器的使用位置。 在viewWillAppear中将flag false ，因为每次对其进行更新都是可以实现的最简单的方法。

class ViewController1: UIViewController {
      var isFromVC2 = false
      var isFromVC3 = false

     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(true)
         isFromVC2 = false
         isFromVC3 = false
     }

}


class ViewController2: UIViewController {


 //You can call this function from where you want otherwise you can make it global.
    func navigateToVC1() {
        let viewController1 = self.storyboard?.instantiateViewController(withIdentifier: "ViewController1") as! ViewController1
        viewController1.isFromVC2 = true
        self.navigationController?.pushViewController(viewController1, animated: true)
    }


}

class ViewController3: UIViewController {

    func navigateToVC1() {
        let viewController1 = self.storyboard?.instantiateViewController(withIdentifier: "ViewController1") as! ViewController1
        viewController1.isFromVC3 = true
        self.navigationController?.pushViewController(viewController1, animated: true)
    }

}