ios 监听系统键盘的出现和消失

//注册键盘出现的通知

[[NSNotificationCenter
defaultCenter] addObserver:self

selector:@selector(keyboardWasShown:)

name:UIKeyboardWillShowNotification
object:nil];

//注册键盘消失的通知

[[NSNotificationCenter
defaultCenter] addObserver:self

selector:@selector(keyboardWillBeHidden:)

name:UIKeyboardWillHideNotification
object:nil];

- (void)keyboardWasShown:(NSNotification*)aNotification

{

//键盘高度

CGRect keyBoardFrame = [[[aNotification
userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey]
CGRectValue];

}

-(void)keyboardWillBeHidden:(NSNotification*)aNotification

{

}