//当键盘出现或改变时调用
- (void)keyboardWillShow:(NSNotification *)aNotification
{
//获取键盘的高度
NSDictionary *userInfo = [aNotification userInfo];
NSValue *aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
CGRect keyboardRect = [aValue CGRectValue];
int height = keyboardRect.size.height;
}
