如何实现didSelectViewController [英] How to implement didSelectViewController

问题描述

我想在有人在选项卡之间切换时捕获事件.我的appdelegate文件中具有以下两个功能:

I want to catch the event when someone switches between tabs. I have the following two function in my appdelegate file:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    UITabBarController * uitbc = [storyboard instantiateViewControllerWithIdentifier:@"tabbarcontroller"];
    uitbc.delegate = self;
    [self.window addSubview:uitbc.view];

    return YES;
}


- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
    NSLog(@"switching");
}

但是NSLog(@"switching");从不触发. xcode对行uitbc.delegate = self;发出警告，说将appdelegate const__strong传递给不兼容类型id的参数".

But the NSLog(@"switching"); never fires. The xcode issues a warning for the line uitbc.delegate = self; saying "Passing appdelegate const__strong to parameter of incompatible type id".

我做错了什么?除了要实例化tabbarcontroller表单故事板之外，我只是在这里找到公认的答案:

What am I doing wrong? I'm just following the accepted answer found here, except i'm instantiating my tabbarcontroller form story board:

如何获取切换事件iPhone上的标签菜单

更新 基于skram的建议，我为我的appdelegate编写了此代码，但NSLOG(Switching)仍然不触发:

Update Based on skram's suggestion, I wrote this for my appdelegate but the NSLOG(Switching) still doesn't fire:

@interface johnAppDelegate : UIResponder <UITabBarControllerDelegate>

我还更新了didFinishLauchingWithOptions:

I also updated my didFinishLauchingWithOptions:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
tabBarController = self.window.rootViewController.tabBarController;
tabBarController.delegate = self;
[window addSubview:tabBarController.view];
}

好消息是没有崩溃.我也不再对不兼容类型发出警告.但仍然，didSelectViewController不会触发.

Good thing is that nothing crashes. I also no longer et the warning about incompatible types. But still, didSelectViewController doesn't fire.

推荐答案

在我的appdelegate.h文件中，我更改了该行

in my appdelegate.h file, I changed the line

@interface wscAppDelegate : UIResponder <UIApplicationDelegate>

到

@interface wscAppDelegate : UIResponder <UIApplicationDelegate,UITabBarControllerDelegate>

然后在我的CustomTabBarController的viewDidLoad函数中，添加了以下几行:

Then in my CustomTabBarController in the viewDidLoad function i added these lines:

wscAppDelegate *appDelegate = (wscAppDelegate *)[[UIApplication sharedApplication] delegate];
self.delegate = appDelegate;

然后在appdelegate.m文件中，我添加了此功能

Then in appdelegate.m file, I added this function

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{

NSLog(@"hooray this works");

}

这篇关于如何实现didSelectViewController的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！