iPhone - 在选项卡栏中切换视图控制器并调用方法

发布于 2024-08-17 11:36:10 字数 1031 浏览 2 评论 0原文

我的应用程序中有一个 TabBar，我在 AppDelegate 中执行此操作：

...
test2ViewController = [[Test1ViewController alloc] init];
...
navigationTest2Controller = [[UINavigationController alloc] initWithRootViewController:test2ViewController];

NSArray *myControllers = [NSArray arrayWithObjects:..., navigationTest2Controller, nil];
[self.myTabBarController setViewControllers:myControllers animated:NO];

现在我遇到的问题是我位于 ViewController 中，并且我想切换到“navigationTest2Controller”。我在我的 AppDelegate 中执行此操作：

self.myTabBarController.selectedViewController = navigationTest2Controller;

这有效。它切换到这个 ViewController！这个ViewController已经被加载并且viewDidLoad方法被调用。在此 viewDidLoad 方法中是一个方法调用：

[self myMethod];

我希望，如果视图切换到此 ViewController，则应始终调用此“myMethod”。我该怎么做？在我的 AppDelegate 行之前

self.myTabBarController.selectedViewController = navigationTest2Controller;

???或者是否有另一个委托在每次选择/切换到 ViewController 时都会被调用？

有人知道这个吗？

预先非常感谢&此致。

原文

I have a TabBar in my application and I do this in my AppDelegate:

...
test2ViewController = [[Test1ViewController alloc] init];
...
navigationTest2Controller = [[UINavigationController alloc] initWithRootViewController:test2ViewController];

NSArray *myControllers = [NSArray arrayWithObjects:..., navigationTest2Controller, nil];
[self.myTabBarController setViewControllers:myControllers animated:NO];

Now I have the problem that I am in a ViewController and I want to switch to the "navigationTest2Controller". I do this in my AppDelegate with:

self.myTabBarController.selectedViewController = navigationTest2Controller;

This works. It switches to this ViewController! This ViewController was already loaded and the viewDidLoad method was called. In this viewDidLoad method is a methos call:

[self myMethod];

I want, that if the view switches to this ViewController this "myMethod" should always be called.
How can I do this? In my AppDelegate before the line

self.myTabBarController.selectedViewController = navigationTest2Controller;

??? Or is there another delegate which will be called every time the ViewController is selected/switched to?

Does anyone know this?

Thanks a lot in advance & Best Regards.

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多孤肩上扛 2024-08-24 11:36:10

您应该将视图可见时要运行的任何代码放置在 -viewWillAppear: 或 -viewDidAppear 视图控制器的方法。

编辑：要使这种情况发生仅当您从某个视图切换时，您可以子类化UITabBarController，仅修改< code>–tabBarController:shouldSelectViewController: 方法。在该方法中，您可以执行以下操作：

- (BOOL)tabBarController:(UITabBarController *)tabBarController
shouldSelectViewController:(UIViewController *)viewController
{
    if (self.selectedIndex == 1 &&
        [viewController respondsToSelector:@selector(myMethod)]) {
        [viewController myMethod];
    }

    return YES;
}

You should place any code that you want to run when the view becomes visible in the -viewWillAppear: or -viewDidAppear method of your view controller.

EDIT: To make this happen only when you switch from a certain view, you can subclass UITabBarController, only modifying the –tabBarController:shouldSelectViewController: method. In that method, you could do something like this:

- (BOOL)tabBarController:(UITabBarController *)tabBarController
shouldSelectViewController:(UIViewController *)viewController
{
    if (self.selectedIndex == 1 &&
        [viewController respondsToSelector:@selector(myMethod)]) {
        [viewController myMethod];
    }

    return YES;
}

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