iOS 键盘动画

首先注册通知，监听键盘的变动：

   NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
   NSOperationQueue *mainQuene =[NSOperationQueue mainQueue];
    [nc addObserverForName:UIKeyboardWillChangeFrameNotification
                    object:nil
                     queue:mainQuene
                usingBlock:^(NSNotification *note){
                    [weakSelf keyboardWillChangeFrame:note];
                }];
    [nc addObserverForName:UIKeyboardWillShowNotification
                    object:nil
                     queue:mainQuene
                usingBlock:^(NSNotification *note){
                  [weakSelf keyboardWillShow:note];
                }];
    [nc addObserverForName:UIKeyboardWillHideNotification
                    object:nil
                     queue:mainQuene
                usingBlock:^(NSNotification *note){
                    [weakSelf keyboardWillHide:note];
               }];

键盘的frame和动画属性通知里都有，直接获取：

- (void)layoutView:(NSNotification *)noti {
         //获取键盘高度
  NSDictionary *userInfo = notification.userInfo;
    CGRect endFrame   = [userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    _keyboardHeight = _isVisiable? endFrame.size.height: 0;
        //获取键盘动画属性
    UIViewAnimationOptions animationCurve = [userInfo[UIKeyboardAnimationCurveUserInfoKey] integerValue];
    CGFloat animationDuration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue];
   [UIView animateWithDuration:animationDuration
                          delay:0.0
                        options:animationCurve
                     animations:^{
                  //改变界面布局
                     } completion:nil];
}