视图控制器:如何以编程方式在视图之间切换? [英] View Controllers: How to switch between views programmatically?

问题描述

简而言之:我想要两个全屏视图，我可以在视图 A 和视图 B 之间切换.我知道我可以只使用 Tab Bar Controller，但我不想.我想看看这是如何手动完成的，以了解幕后发生的事情.

In short: I want to have two fullscreen views, where I can switch between view A and view B. I know I could just use an Tab Bar Controller, but I dont want to. I want to see how this is done by hand, for learning what's going on under the hood.

我有一个 UIViewController 作为根控制器:

I have an UIViewController that acts as an root controller:

@interface MyRootController : UIViewController {
    IBOutlet UIView *contentView;
}
@property(nonatomic, retain) UIView *contentView;

@end

contentView 连接到一个 UIView，我将它作为子视图添加到 Nib 的视图"中.它是绿色的，我全屏看到它.工作正常.

The contentView is hooked up to an UIView which I added as an subview to the "view" of the Nib. This has green color and I see it fullscreen. Works fine.

然后，我以几乎相同的方式创建了另外两个视图控制器.ViewControllerA 和 ViewControllerB.ViewControllerA 有蓝色背景，ViewControllerB 有黑色背景.只是为了看看哪个是活跃的.

Then, I created two other View Controllers pretty much the same way. ViewControllerA and ViewControllerB. ViewControllerA has a blue background, ViewControllerB has a black background. Just to see which one is active.

所以，在myRootController的实现中，我是这样做的:

So, in the implementation of myRootController, I do this:

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];

    ViewControllerA *vcA = [[ViewControllerA alloc] initWithNib];
    [self.contentView addSubview:vcA.view];

    [cvA release];
}

顺便说一下，-initWithNib 方法如下所示:

By the way, the -initWithNib method looks like this:

- (id)initWithNib { // Load the view nib
    if (self = [super initWithNibName:@"ViewA" bundle:nil]) {
        // do ivar initialization here, if needed
    }
    return self;
}

那行得通.当我启动应用程序时，我看到了 ViewControllerA 的视图.但现在最大的问题是:视图控制器通常具有所有这些方法，例如:

That works. I see the view from ViewControllerA when I start the app. But now the big question is: A View Controller typically has all those methods like:

• (void)viewWillAppear:(BOOL)animated;
• (void)viewDidDisappear:(BOOL)animated;
• (void)viewDidLoad;

...等等.如果我在没有标签栏控制器的情况下以我的"方式执行这些方法，谁或什么，或者如何调用这些方法?我的意思是:如果我分配那个 ViewController 的类并且视图是可见的，我是否需要注意调用这些方法?它如何知道 viewWillAppear、viewDidDisappear 或 viewDidLoad?我相信 Tab Bar Controller 在幕后拥有所有这些聪明".还是我错了?

...and so on. Who or what, or how would those methods be called if I do it "my" way without a tab bar controller? I mean: If I allocate that ViewController's class and the view get's visible, would I have to take care about calling those methods? How does it know that viewWillAppear, viewDidDisappear, or viewDidLoad? I believe that the Tab Bar Controller has all this "cleverness" under the hood. Or am I wrong?

更新:我已经测试过了.如果我释放视图控制器(例如:ViewControllerA)，我将不会在 viewDidDisappear 上收到任何日志消息.只有在分配和初始化 ViewControllerA 时，我才会得到一个 viewDidLoad.但就是这样.所以现在所有的迹象都代表 UITabBarController 的聪明;) 我必须弄清楚如何复制它，对吗?

UPDATE: I've tested it. If I release the view controller (for example: ViewControllerA), I will get no log message on viewDidDisappear. Only when allocating and initializing the ViewControllerA, I get an viewDidLoad. But that's it. So all signs stand for the cleverness of UITabBarController now ;) and I have to figure out how to replicate that, right?

推荐答案

可以从最简单的removeFromSuperview/insertSubview开始，一点一点的往里面添加代码.

You can begin from the simplest removeFromSuperview/insertSubview and add code to it little by little.

//SwitchViewController.h
#import 
@class BlueViewController;
@class YellowViewController;

@interface SwitchViewController : UIViewController {
    IBOutlet BlueViewController *blueViewController;
    IBOutlet YellowViewController *yellowViewController;
}
- (IBAction)switchViews:(id)sender;
@property (nonatomic, retain) BlueViewController *blueViewController;
@property (nonatomic, retain) YellowViewController *yellowViewController;
@end

//1. remove yellow view and insert blue view
- (IBAction)switchViews:(id)sender {
    if(self.blueViewController.view.superview == nil)
    {
        [yellowViewController.view removeFromSuperview];
        [self.view insertSubview:blueViewController.view atIndex:0];
    }
}

//2. appear=insert, disappear=remove
if(blueViewController.view.superview == nil)
{
    [blueViewController viewWillAppear:YES];
    [yellowViewController viewWillDisappear:YES];

    [yellowViewController.view removeFromSuperview];
    [self.view insertSubview:self.blueViewController.view atIndex:0];

    [yellowViewController viewDidDisappear:YES];
    [blueViewController viewDidAppear:YES];
}

//3. now add animation
[UIView beginAnimations:@"View Flip" context:nil];
[UIView setAnimationDuration:1.25];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
//blue view will appear by flipping from right
if(blueViewController.view.superview == nil)
{
    [UIView setAnimationTransition: UIViewAnimationTransitionFlipFromRight 
                            forView:self.view cache:YES];

    [blueViewController viewWillAppear:YES];
    [yellowViewController viewWillDisappear:YES];

    [yellowViewController.view removeFromSuperview];
    [self.view insertSubview:self.blueViewController.view atIndex:0];

    [yellowViewController viewDidDisappear:YES];
    [blueViewController viewDidAppear:YES];
}
[UIView commitAnimations];

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