// 解决键盘遮挡问题
//选择didShow是因为需要键盘的高度
//选择willHide是因为视图frame重置需要优先于键盘消失，否则表现得不连贯

      [[NSNotificationCenter defaultCenter] addObserver:self

                                               selector:@selector(keyboardWasShown:)

                                                   name:UIKeyboardDidShowNotification

                                                 object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(keyboardWasHide:)

                                                 name:UIKeyboardWillHideNotification

                                               object:nil];

-(void)keyboardWasShown:(NSNotification*)notification

{

    //获取键盘高度

    NSValue* value=notification.userInfo[UIKeyboardFrameBeginUserInfoKey];

    CGFloat keyBoradHeight=[value CGRectValue].size.height;

    NSNumber* animationTime=notification.userInfo[UIKeyboardAnimationDurationUserInfoKey];

    double time=[animationTime doubleValue];

    //获取被遮挡控件距离controller底部的距离

    float a=self.view4.frame.origin.y+self.view4.frame.size.height;

    float b = self.view.frame.size.height-a;

    if (b<keyBoradHeight)

    {

        //动画效果

        [UIView animateWithDuration:time

                         animations:^

         {

             //键盘被挡住了

             CGRect viewCGrect=self.view.frame;

             //视图应该上移所以是－

             viewCGrect.origin.y=viewCGrect.origin.y-(keyBoradHeight-b);

             [self.view setFrame:viewCGrect];

         } completion:nil];

    }

}

-(void)keyboardWasHide:(NSNotification*)notification

{

    NSValue* value=notification.userInfo[UIKeyboardFrameBeginUserInfoKey];

    CGFloat keyBoradHeight=[value CGRectValue].size.height;

    float a=self.view4.frame.origin.y+self.view4.frame.size.height;

    float b = self.view.frame.size.height-a;

         CGRect viewCGrect=self.view.frame;

         viewCGrect.origin.y=viewCGrect.origin.y+(keyBoradHeight-b);

         [self.view setFrame:viewCGrect];

}

-(void)viewWillDisappear:(BOOL)animated

{

    [super viewWillDisappear:animated];

    [[NSNotificationCenter defaultCenter] removeObserver:self

                                                    name:UIKeyboardWillHideNotification

                                                  object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self

                                                    name:UIKeyboardDidShowNotification

                                                  object:nil];

}