Use of IOS notifications

IOS notifications are an important point of knowledge that is often used, and a summary record.

1. Registration Notice to Notification Center

[[Nsnotificationcenter Defaultcenter] addobserver:self selector: @selector (tfchangedvalue:) Name:@ "  Hello"object: nil";

2. Send Notifications

-(BOOL) TextField: (Uitextfield *) TextField Shouldchangecharactersinrange: (nsrange) range replacementstring: ( NSString *)string{    [[Nsnotificationcenter Defaultcenter] Postnotificationname:@ " Hello " Object:string];     return YES;}

3. Receive notifications

Tfchangedvalue: Is the method that responds to receiving notifications, which is called when a notification is received. Name is the name of this notification.

-(void) Tfchangedvalue: (nsnotification*) notif{    NSLog (@ "TextField have changed, now the Textfield.text is%@", Notif.object);} 

4. Notice of Destruction

When it is necessary to destroy, it can be removed according to the name of the notification.

-(void) dealloc{    [[Nsnotificationcenter Defaultcenter] removeobserver:self name:@ " Hello " Object : nil];}

For convenience, I just change the value of a page in the TextField to send a notification, after receiving the notification, the value printed out, entered an NBA, the results are as follows:

Use of IOS notifications