iOS:如何让一个视图触发另一个视图的更新? [英] iOS: how can I make one view trigger an update in another?

问题描述

我的顶层 UIView 包含一些标签和绘图画布.绘图画布本身是一个 UIView，它覆盖了它的 drawRect() method，当然还有各种 touch 方法.当用户完成绘图后，我想更新画布外的一个或多个标签(即都是顶级 UIView 的所有组件).

My top level UIView contains a some labels and a drawing canvas. The drawing canvas is itself a UIView which overrides its drawRect() method and, of course, the various touch methods. When the user has finished drawing, I want to update one or more labels that are outside the canvas (i.e. are all components of the top level UIView).

最好的方法是什么?
我目前有顶级 UIViewController 将各种标签从顶级 传递到我的 CanvasViewsviewDidLoad() method 并且我将它们存储在本地.每当我需要更新标签时，我都会从我拥有的这些兄弟视图的本地副本中进行更新 - 但我对此并不满意，因为它感觉很笨拙.

What's the best way to do it?
I currently have the top level UIViewController pass the various labels into my CanvasViews from the top level viewDidLoad() method and I store them locally. Whenever I need to update a label, I do so from the local copies of these sibling views I have - But I'm not happy with this because it feels kludgy.

为了进一步解释，这就是我在顶级 UIViewController 中所做的:

To explain further, this is what I do in my top level UIViewController:

@IBOutlet weak var myLabel: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()

    for v in self.view.subviews {
        if v .isKindOfClass(CanvasView) {
            let canvasView = v as CanvasView
            canvasView.setMyLabel(myLabel)
        }
    }
}

然后在我的 CanvasView.swift 文件中，我有:

And then in my CanvasView.swift file, I have:

private var myLabel: UILabel!

...

override func touchesEnded(touches: NSSet, withEvent event: UIEvent) {
    // do stuff ...
    setNeedsDisplay()
    myLabel.text = "etc.etc."
}

有没有更好的方法?

谢谢.
大道

推荐答案

如果您的画布是一个单独的 viewController，您可以使用委托协议从画布视图控制器访问您的基本视图控制器.假设您有一个 BaseViewController 调用 canvasViewController.

If your canvas is a separate viewController, you can use delegate protocols to access your base view controller from the canvas view controller. Suppose you have a BaseViewController which calls the canvasViewController.

在您的 canvasViewController.h 中添加以下内容:

In your canvasViewController.h add the following :

@protocol CanvasDelegate <NSObject>
@required
//examples . add your methods to upgate labels here
    - (void) updateLabels: (NSString*) labelText1 and:(NSString*)labelText2;
@end

@interface canvasViewController : UIViewController
{
    id<CanvasDelegate> delegate;
}

@property (retain) id delegate;

@end

现在从你的 canvasViewController.m 文件中执行这段代码，只要你想更新你的标签(或要求 baseViewController 做一些事情):

Now from your canvasViewController.m file execute this code whenever you want to update your labels (or ask the baseViewController to do something) :

[[self delegate] updateLabels:string1 and:string2];

现在为了让您的基本视图控制器接受来自画布的消息，BaseVC 必须采用"CanvasDelegate 协议并实现所需的方法.在 baseViewController.h 中，添加以下内容:

Now for your base view controller to accept messages from the canvas, the BaseVC has to "adopt" the CanvasDelegate Protocol and also implement the required methods. In baseViewController.h, add the following :

@interface baseViewController : UIViewController <CanvasDelegate>

在baseViewController.m中为pushing创建canvasViewController对象时，添加如下命令:

In baseViewController.m when you create an object of canvasViewController for pushing, add the following command :

canvasVC.delegate = self;

并且不要忘记在 baseViewController.m 中实现所需的方法，如下所示:

And don't forget to implement the required methods in baseViewController.m like so :

- (void) updateLabels: (NSString*) labelText1 and:(NSString*)labelText2
{
    //update your labels here
}

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