iOS键盘高度的官方获取方法

处理键盘事件的正确方法是这样的:(包括获取键盘的高度以及键盘弹出和消失动画的时间)
1)在要使用键盘的视图控制器中,接收键盘事件的通知:

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
       [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
        // 键盘高度变化通知,ios5.0新增的
#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

获取到当前keyboard的高度以及动画时间,然后对视图进行对应的操作即可。

#pragma mark - #pragma mark Responding to keyboard events
- (void)keyboardWillShow:(NSNotification *)notification {
/* Reduce the size of the text view so that it's not obscured by the keyboard. Animate the resize so that it's in sync with the appearance of the keyboard. */
 NSDictionary *userInfo = [notification userInfo];
// Get the origin of the keyboard when it's displayed.
 NSValue* aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
// Get the top of the keyboard as the y coordinate of its origin in self's view's coordinate system. The bottom of the text view's frame should align with the top of the keyboard's final position.
 CGRect keyboardRect = [aValue CGRectValue];
// Get the duration of the animation.
 NSValue *animationDurationValue = [userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
 NSTimeInterval animationDuration;
 [animationDurationValue getValue:&animationDuration];
// Animate the resize of the text view's frame in sync with the keyboard's appearance.
 [self moveInputBarWithKeyboardHeight:keyboardRect.size.height withDuration:animationDuration];
}
- (void)keyboardWillHide:(NSNotification *)notification {
 NSDictionary* userInfo = [notification userInfo];
/* Restore the size of the text view (fill self's view). Animate the resize so that it's in sync with the disappearance of the keyboard. */
 NSValue *animationDurationValue = [userInfo  objectForKey:UIKeyboardAnimationDurationUserInfoKey];
 NSTimeInterval animationDuration;
 [animationDurationValue getValue:&animationDuration];
 [self moveInputBarWithKeyboardHeight:0.0 withDuration:animationDuration];
}
[[NSNotificationCenter defaultCenter] removeObserver:self];

ps:
ios5隐藏功能分享——“字典”功能(英英字典):
在任何输入框中选中一个英文单词,此时会有选择项“复制”,“删除”…等,还有一个向右的箭头,点击这个向右的箭头后,就会出现“定义”选项,点击这个“定义”按钮即会弹出这个英语单词的英文解释。
原文链接
http://www.cnblogs.com/zhulin/archive/2011/10/15/2213687.html