segue创建视图控制器swift的新实例

Question

我有一个应用程序与四个视图控制器。 1，2和3之间的导航是好的，但从视图控制器1你可以选择2或4（这是我的设置）我有一个从1到4的segue。然后我使用unwind segue来取回。但是当我使用segue回到4时，它实例化了一个新的实例4.

我的问题：有没有什么办法可以访问用户上次看到的视图控制器的同一个实例。

Answer 1

就像什么@ Paul11在评论中说，你应该保持的UIViewController你试图推，如果你想在同一实例进行访问

比方说一个参考

var someViewController = SomeViewController() // << this is at the class level scope 

func someSampleFunc() { 
    // doing this would create a new instance of the `SomeViewController` every time you push 
    self.navigationController?.pushViewController(SomeViewController(), animated: true) 

    // whereas if you use the variable which is at the class level scope the memory instance is kept 
    self.navigationController?.pushViewController(someViewController, animated: true) 
} 

的情况下

class Bro { 
    var name = "Some Name" 

    func sayDude() {   
     // since `name` is a class level you can access him here 

     let dude = "DUUUUUUUDE" // this variable's lifetime only exists inside the `sayDude` function, therefore everytime you call `sayDude()` a new instance of `dude` is created 

     print(name) 
     print(dude) 
    } 

    func doBackflip() { 
     sayDude() // 

     print(name + " does backflip") // since `name` is a class level you can access him here 
    } 
}