键盘挡住输入框问题

@property (nonatomic,assign)float currentf_heihgt; //当前tf的高度

@property (nonatomic,assign)float currentf_y;  //当前tf的y值，方便获得keyborard移动

#define FUll_VIEW_WIDTH ([[UIScreen mainScreen] bounds].size.width)

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{

    UIWindow * window=[[[UIApplication sharedApplication] delegate] window];

    CGRect rect=[textField convertRect: textField.bounds toView:window];

    _currentf_y = rect.origin.y;

    _currentf_heihgt = textField.frame.size.height;

  return YES;

}

-(void)keyboardWillShow:(NSNotification*)aNotification {

    //获取键盘的高度

    NSDictionary *userInfo = [aNotification userInfo];

    NSValue *aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];

    CGRect keyboardRect = [aValue CGRectValue];

  CGFloat keyboardheight = keyboardRect.size.height;

    //计算出键盘顶端到inputTextView panel底端的距离(加上自定义的缓冲距离INTERVAL_KEYBOARD)

    //如果大于0，则键盘将输入框遮挡，需调节高度，小于0，则不需要调节

    CGFloat offset = _currentf_y + _currentf_heihgt - (FUll_VIEW_HEIGHT - keyboardheight);

    //取得键盘的动画时间，这样可以在视图上移的时候更连贯

    double duration = [[aNotification.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    //将视图上移计算好的偏移

    NSLog(@"........%f",offset);

    if(offset > 0) {

        [UIView animateWithDuration:duration animations:^{

            blackGroundView.frame = CGRectMake(0.0f,-offset, blackGroundView.frame.size.width, blackGroundView.frame.size.height);

        }];

        NSLog(@"hhhahjfjhsffksfkjs");

    }

}

-(void)keyboardwillHiden:(NSNotification*)notification{

  double duration=  [[[notification userInfo]objectForKey:UIKeyboardAnimationDurationUserInfoKey]doubleValue];

    [UIView animateWithDuration:duration animations:^{

        blackGroundView.frame = CGRectMake(0.0f,NAVIGATION_BAR_HEIGHT, blackGroundView.frame.size.width, blackGroundView.frame.size.height);

    }];

}