iOS8 UIKeyboardWillShowNotification 键盘遮挡问题

iOS8中，键盘呼出会发送UIKeyboardWillShowNotification两次通知，导致在做键盘遮挡问题的时候会减两遍键盘的高度，原因如下：

The reason is the difference in the keyboard. If the second field is a password field this means there is another keyboard under the hood. Therefore the notification is sent twice.

解决方法：

@property(nonatomic, assign) BOOL kbIsOn;

/*

* 注册键盘的通知addObserver

*/

-(void)keyboardWillShow:(NSNotification *)noti

{

　　if(!_kbIsOn)

　　{

　　　　//遮挡操作　　

　　}

　　_kbIsON = YES;

}

 

-(void)keyboardWillHidden

{

　　_kbIsOn = NO;

　　//复原操作

}