如何使用 NSNotificationCenter 传递对象 [英] How to pass object with NSNotificationCenter

问题描述

我正在尝试将一个对象从我的应用程序委托传递给另一个类中的通知接收器.

I am trying to pass an object from my app delegate to a notification receiver in another class.

我想传递整数messageTotal.现在我有:

I want to pass integer messageTotal. Right now I have:

在接收器中:

- (void) receiveTestNotification:(NSNotification *) notification
{
    if ([[notification name] isEqualToString:@"TestNotification"])
        NSLog (@"Successfully received the test notification!");
}

- (void)viewDidLoad {
    [super viewDidLoad];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(dismissSheet) name:UIApplicationWillResignActiveNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveTestNotification:) name:@"eRXReceived" object:nil];

在进行通知的类中:

[UIApplication sharedApplication].applicationIconBadgeNumber = messageTotal;
[[NSNotificationCenter defaultCenter] postNotificationName:@"eRXReceived" object:self];

但我想将对象 messageTotal 传递给另一个类.

But I want to pass the object messageTotal to the other class.

推荐答案

您必须使用userInfo"变体并传递一个包含 messageTotal 整数的 NSDictionary 对象:

You'll have to use the "userInfo" variant and pass a NSDictionary object that contains the messageTotal integer:

NSDictionary* userInfo = @{@"total": @(messageTotal)};

NSNotificationCenter* nc = [NSNotificationCenter defaultCenter];
[nc postNotificationName:@"eRXReceived" object:self userInfo:userInfo];

在接收端，您可以按如下方式访问 userInfo 字典:

On the receiving end you can access the userInfo dictionary as follows:

-(void) receiveTestNotification:(NSNotification*)notification
{
    if ([notification.name isEqualToString:@"TestNotification"])
    {
        NSDictionary* userInfo = notification.userInfo;
        NSNumber* total = (NSNumber*)userInfo[@"total"];
        NSLog (@"Successfully received test notification! %i", total.intValue);
    }
}

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