如何删除以前的ViewController [英] How to Remove a Previous ViewController

问题描述

我是一名学生，对编程很陌生。我想在业余时间学习Objective-C / Swift。我使用带有多个菜单/场景的swift的spriteKit制作了一个游戏。

I am a student and pretty new to programming. I am trying to learn Objective-C/Swift in my spare time. I made a game using spriteKit with swift that has multiple menus/scenes.

我正在尝试从一个视图控制器转换到另一个视图控制器。为此，我使用了以下代码：

I am trying to transition from one view controller to another. To do this I used this code:

@IBAction func PlayButtonPressed(sender: AnyObject) {
    let playStoryboard : UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let vc : UIViewController = playStoryboard.instantiateViewControllerWithIdentifier("playGame") as UIViewController
    self.presentViewController(vc, animated: true, completion: nil)
}

这适用于过渡到新的VC场景，不过，我相信以前的VC仍然在堆栈中并占用内存，从而减慢了我的程序速度。

This works for transitioning to the new VC scene, however, I believe the previous VC is still in the stack and takes up memory, slowing down my program.

我读过其他一些帖子，你可以使用导航控制器删除VC。但是，我没有导航控制器;只查看控制器。我见过一些关于 removeFromParentViewController（）和 view.removeFromSuperview（）的东西，但我真的不知道如何实现它。除此之外我找不到我想要的答案。

I've read on some other posts that you can use the navigation controller to remove VC. However, I do not have a navigation controller; only view controllers. I've seen some stuff about removeFromParentViewController() and view.removeFromSuperview(), but I don't really know how to implement it. Other than that I did not find an answer that I was looking for.

所以我问的问题是如何从堆栈中删除以前的VC？任何帮助将是一个赞赏！ （希望帮助很快，但Objective-C也有帮助）提前感谢你！

So the question I am asking is how do I remove the previous VC from the stack? Any help would be a appreciated! (would prefer the help to be in swift, but Objective-C would help also) Thank you in advance!

注意参考：我相信Objective-C我的代码看起来像这样：

note for reference: I believe in Objective-C my code would look something like this:

-(IBAction) PlayButtonPressed: (id) sender {
    UIStoryboard *playStoryboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
    UIViewController *vc = [playStoryboard instantiateViewControllerWithIdentifier:@"playGame"];
    [self presentViewController:vc animated:YES completion:nil];
}

推荐答案

我可以假设，查看屏幕上显示的控制器自动从主故事板或通过设置应用程序的 window.rootViewController 属性进行实例化。

As I can assume, view controller being presented on the screen was instantiated either automatically from main storyboard or by setting app's window.rootViewController property.

在任何一种情况下，您都可以再次设置 rootViewController 作为 vc 。要更改应用程序的rootViewController，您需要替换以下代码行：

In either case you can set rootViewController again to be your vc. To change rootViewController of your app you need to replace this line of code:

self.presentViewController(vc, animated: true, completion: nil)

...其中一个选项如下。

... with one of the options bellow.

Objective-C

UIWindow *window = (UIWindow *)[[UIApplication sharedApplication].windows firstObject];
window.rootViewController = vc;

Swift

let window = UIApplication.sharedApplication().windows[0] as UIWindow;
window.rootViewController = vc;

使用过渡动画导航：

Objective-C

UIWindow *window = (UIWindow *)[[UIApplication sharedApplication].windows firstObject];
[UIView transitionFromView:window.rootViewController.view
                    toView:vc.view
                  duration:0.65f
                   options:UIViewAnimationOptionTransitionCrossDissolve // transition animation
                completion:^(BOOL finished){
                    window.rootViewController = vc;
                }];

Swift

let window = UIApplication.sharedApplication().windows[0] as UIWindow;
UIView.transitionFromView(
    window.rootViewController.view,
    toView: vc.view,
    duration: 0.65,
    options: .TransitionCrossDissolve,
    completion: {
        finished in window.rootViewController = vc
    })

备注：
一旦rootViewController值被更改，原始视图控制器引用计数应该变为0，因此它将从内存中删除！

Remarks: Once rootViewController value gets changed your original view controller reference count should became 0 hence it will be removed from the memory!

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