Demonstration of Data Transmission Mechanism for iPhone development 01. nsnotification

I. demonstration using nsnotification and uialertveiw: communication between a notification (usually the one that sends the message) and an observer (the one that receives the message. Notifications and observers are two mutually independent classes. Program effect: (1) first create a class inherited from uiviewcontroller: myobserver. h. (As the observer) 1) myobserver. h [Plain]View plaincopy

1. # Import <uikit/uikit. h>
2. # Import "myclass. H"
3. @ Interface myobserver: uiviewcontroller
4. @ Property (retain) myclass * myclass;
5. -(Void) updata :( nsnotification *) notifi;
6. @ End

1) myobserver. m [Plain]View plaincopy

1. # Import "myobserver. H"
3. @ Implementation myobserver
5. @ Synthesize myclass;
7. -(Void) viewdidload
8. {
9. // Note that the myclass must be a global variable and cannot be written like myclass * myclass = [[myclass alloc] init.
10. Self. myclass = [[myclass alloc] init];
12. // Define the pop-up dialog box. Note that the delegate: myclass must be myclass so that myclass can perform the operation after clicking the button.
13. Uialertview * Alert = [[uialertview alloc] initwithtitle: @ "hello" message: @ "dongstone" delegate: myclass cancelbuttontitle: @ "cancle" success: @ "back", nil];
15. // Add a class to the notification to make it an observer to receive messages. Self indicates the current class. selector: The method to be executed after the notification is received. Name: indicates the pass that is matched when a message is sent (Object: notification within the range. Here object: Nil is a notification that can be sent of any type. Both the name and object conditions must be met.
16. [[Nsicationcenter center defacenter center] addobserver: Self selector: @ selector (updata :) name: @ "pass" Object: Nil];
17. // Display the dialog box
18. [Alert show];
19. [Super viewdidload];
20. // Do any additional setup after loading the view from Its nib.
21. }
22. // This method is customized for receiving data
23. -(Void) updata :( nsnotification *) notifi {
24. Nsstring * STR = [[notifi userinfo] objectforkey: @ "key"];
25. Uialertview * Al = [[uialertview alloc] initwithtitle: @ "The message has been passed in." message: Str delegate: Self cancelbuttontitle: Nil otherbuttontitles: Nil];
26. [Al show];
27. }

(2) create a common class (myclass. h) (inheriting everything, because this program does not need to have too many functions ). (As notification)

2) myclass. h

 

[Plain]View plaincopy

1. # Import <Foundation/Foundation. h>
3. @ Interface myclass: nsobject <uialertviewdelegate>
5. @ End

2) myclass. m

 

 

 

 

 

[Plain]View plaincopy

1. # Import "myclass. H"
3. @ Implementation myclass
5. -(ID) Init
6. {
7. Self = [Super init];
8. If (Self ){
9. }
10. Return self;
11. }
12. // Implementation Method
13. -(Void) alertview :( uialertview *) alertview clickedbuttonatindex :( nsinteger) buttonindex {
15. // The type that the method userinfo can receive is nsdictionary.
16. Nsstring * STR = [[nsstring alloc] initwithformat: @ "The subscript of the clicked button is: % d", buttonindex];
17. Nsdictionary * DIC = [[nsdictionary alloc] initwithobjectsandkeys: Str, @ "key", nil];
19. // Send the message. @ "pass" matches the notification name, object: Nil notification class range
20. [[Nsicationcenter center defacenter center] postnotificationname: @ "pass" Object: Nil userinfo: DIC];
21. }
23. @ End

Illustration: