如何通过NSNotificationCenter传递对象?

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我想从我的应用程序委托传递一个对象到另一个类中的通知接收器。

我想传递整数messageTotal。现在我有:

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];

在正在进行通知的类中:

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

但我想将对象传递messageTotal给另一个类。

提问于
用户回答回答于

使用“userInfo”变量并传递包含messageTotal整数的NSDictionary对象:

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

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

在接收端,可以按如下方式访问userInfo字典:

-(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);
    }
}
用户回答回答于

一个传递自定义数据对象的示例

Class A (sender):

YourDataObject *message = [[YourDataObject alloc] init];
// set your message properties
NSDictionary *dict = [NSDictionary dictionaryWithObject:message forKey:@"message"];
[[NSNotificationCenter defaultCenter] postNotificationName:@"NotificationMessageEvent" object:nil userInfo:dict];

Class B (receiver):

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[NSNotificationCenter defaultCenter]
     addObserver:self selector:@selector(triggerAction:) name:@"NotificationMessageEvent" object:nil];
}

#pragma mark - Notification
-(void) triggerAction:(NSNotification *) notification
{
    NSDictionary *dict = notification.userInfo;
    YourDataObject *message = [dict valueForKey:@"message"];
    if (message != nil) {
        // do stuff here with your message data
    }
}

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