NSNotification 'object' 和 'userInfo' 有什么区别？

Question

NSNotification 的 object 和 userInfo 有什么区别？

当我 post 一个带有参数的通知时，我可以使用 object 或 userInfos 来完成它。但是我不知道这两种方式有什么区别。

使用 userInfo 有什么优势吗？或者使用 object 就够了吗？

Answer 1

如果您定义一个对象，您可以过滤仅由该对象发送的通知。例如，如果您注册一个通知，将一个对象指定为 notificationSender，即使通知名称与其他发布的通知相同，您也只能从该对象收到通知：

- (void)addObserver:(id)notificationObserver
       selector:(SEL)notificationSelector
           name:(NSString *)notificationName
         object:(id)notificationSender

这里来自 Apple 文档：

notificationSender The object whose notifications the observer wants to receive; that is, only notifications sent by this sender are delivered to the observer.

If you pass nil, the notification center doesn’t use a notification’s sender to decide whether to deliver it to the observer.

Answer 2

When working with an NSNotification object, you’ll want to familiarize yourself the userInfo dictionary, which provides access to any additional objects that may be of interest to the receiver. Understanding the object method may also be helpful if you are using the same notification on more than one object.

有关详细信息，请阅读此 link。

http://iosdevelopertips.com/cocoa/nsnotification-userinfo-and-object-methods.html

Answer 3

object 表示发布通知的对象。 userInfo 包含用于接收 object/function 的附加 information/data。

根据NSNotificationCenter Class Reference：

postNotificationName:object:userInfo:

Creates a notification with a given name, sender, and information and posts it to the receiver.

Declaration

Swift
func postNotificationName(_ notificationName: String, object notificationSender: AnyObject?, userInfo userInfo: [NSObject : AnyObject]?)
Objective-C
- (void)postNotificationName:(NSString *)notificationName object:(id)notificationSender userInfo:(NSDictionary *)userInfo
Parameters

notificationName

The name of the notification.

notificationSender

The object posting the notification.

userInfo

Information about the the notification. May be nil.

Discussion

This method is the preferred method for posting notifications.

NSNotification 'object' 和 'userInfo' 有什么区别？

What's Difference between NSNotification 'object' and 'userInfo'?

nsnotification

ios

Declaration

Parameters

Discussion