iOS5键盘弹出view自适应

[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
    
#ifdef __IPHONE_5_0
    float version = [[[UIDevice currentDevice] systemVersion] floatValue];
    if (version >= 5.0) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillChangeFrameNotification object:nil];
    }
#endif

#pragma -
#pragma keyboard notification
- (void)keyboardWillShow:(NSNotification*)notification {
    NSDictionary *userInfo = [notification userInfo];
    
    NSValue* aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
    
    CGRect keyboardRect = [aValue CGRectValue];
    
    NSValue *animationDurationValue = [userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
    NSTimeInterval animationDuration;
    [animationDurationValue getValue:&animationDuration];
    
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:animationDuration];
    
    ... do something ...
    
    [UIView commitAnimations];
}

- (void)keyboardWillHide:(NSNotification*)notification {
    NSDictionary *userInfo = [notification userInfo];
    
    NSValue* aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
    
    CGRect keyboardRect = [aValue CGRectValue];
    
    NSValue *animationDurationValue = [userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
    NSTimeInterval animationDuration;
    [animationDurationValue getValue:&animationDuration];

    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:animationDuration];
    
    ... do something ...
    
    [UIView commitAnimations];
}

改变键盘大小时也会更新视图