ios - 从 AppDelegate 向 ViewController 发送通知

Question

需要你的帮助。我将这些委托(delegate)方法实现到 AppDelegate.m:

    -(BOOL)application:(UIApplication *)application
           openURL:(NSURL *)url
 sourceApplication:(NSString *)sourceApplication
        annotation:(id)annotation {
    if (url != nil && [url isFileURL]) {
        //Valid URL, send a message to the view controller with the url
    }
    else {
        //No valid url
    }
    return YES;

但是现在，我需要的 URL 不在 AppDelegate 中，而是在我的 ViewController 中。我如何“发送”他们 url 或者我如何将这些委托(delegate)方法实现到 ViewController？

Answer 1

您可以使用 NSNotificationCenter，如下所示:

首先在您的应用委托(delegate)中发布通知:

NSDictionary *_dictionary=[NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:[NSString stringWithFormat:@"%d",newIndex],nil] forKeys:[NSArray arrayWithObjects:SELECTED_INDEX,nil]];

[[NSNotificationCenter defaultCenter] postNotificationName:SELECT_INDEX_NOTIFICATION object:nil userInfo:_dictionary];

然后注册你想观察这个通知的ViewController为

/***** To register and unregister for notification on recieving messages *****/
- (void)registerForNotifications
{
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(yourCustomMethod:)
                                                 name:SELECT_INDEX_NOTIFICATION object:nil];
}

/*** Your custom method called on notification ***/
-(void)yourCustomMethod:(NSNotification*)_notification
{
    [[self navigationController] popToRootViewControllerAnimated:YES];
    NSString *selectedIndex=[[_notification userInfo] objectForKey:SELECTED_INDEX];
    NSLog(@"selectedIndex  : %@",selectedIndex);

}

在 ViewDidLoad 中调用此方法:

- (void)viewDidLoad
{

    [self registerForNotifications];
}

然后在 UnLoad 上通过调用此方法删除此观察者:

-(void)unregisterForNotifications
{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:SELECT_INDEX_NOTIFICATION object:nil];
}


-(void)viewDidUnload
{
    [self unregisterForNotifications];
}

希望对你有帮助。