ios - segue 创建 View Controller 的新实例 swift

Question

我有一个带有四个 View Controller 的应用程序。 1、2 和 3 之间的导航很好，但从 View Controller 1 中，您可以选择转到 2 或 4(这是我的设置)。我有一个从 1 到 4 的转场。然后我使用展开转场返回。但是当我使用 segue 返回 4 时，它会实例化 4 的新实例。

我的问题:有没有办法访问用户上次拥有的 View Controller 的同一实例。

Answer 1

就像@Paul11在评论中所说的那样，如果您希望访问相同的实例，您应该保留尝试推送的UIViewController的引用

举个例子

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)
}

另一个例子

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
    }
}