轉自：http://www.devdiv.com/home.php?mod=space&uid=65440&do=blog&id=2871

1. 定義一個方法

update

2.訂閱通知

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(update) name:@"update" object:nil]

3. 在要發出通知訊息的地方

[[NSNotificationCenter defaultCenter] postNotificationName:@"update" object:nil];

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虛擬鍵盤顯示和消失的通知

[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(keyboardWasShown:)

name:UIKeyboardDidShowNotification

object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(keyboardWasHidden:)

name:UIKeyboardDidHideNotification

object:nil];

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- (void)keyboardWasShown:(NSNotification *) aNotification{

if(keyboardShown)

return;

NSDictionary *info = [aNotification userInfo];//獲取通知資訊

//get the size of the keyboard.

NSValue *aValue = [info objectForKey:UIKeyboardFrameBeginUserInfoKey];

CGSize keyboardSize = [aValue CGRectValue].size;

//Resize the scroll view

CGRect viewFrame = [scrollView frame];

viewFrame.size.height -= keyboardSize.height;

//Scroll the active text field into view

CGRect textFieldRect = [activeField frame];

[scrollView scrollRectToVisible:textFieldRect animated:YES];

keyboardShown = YES;

}

//Called when the UIKeyboardDidHideNotification is sent

- (void)keyboardWasHidden:(NSNotification *) aNotification{

NSDictionary *info = [aNotification userInfo];

//Get the size of the keyboard.

NSValue *aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey];

CGSize keyboardSize = [aValue CGRectValue].size;

//Reset the height of the scroll view to its original value

CGRect viewFrame = [scrollView Frame];

viewFrame.size.height += keyboardSize.height;

scrollView.frame = viewFrame;

keyboardShown = NO;

}