iOS 键盘弹出视图精准上移

1 视图精准位移，需要计算出输入框距离屏幕底部的距离，然后

计算出输入框需要上移的距离，就是整个视图需要上移的距离,
注意，我们可以自行设置一个适当的buffer,我这里是40，就是输入框距离
键盘有一个40的距离，避免紧挨着 导致体验不佳

- (void)keyboardWillShow:(NSNotification *)noti
{
    UpdateUserInfoView  *userInforView = self.editCell.userInfoView;
    
    CGRect userInfoViewframe = [self.editCell convertRect:userInforView.frame toView:window];
    CGFloat bottomSpace = GetScreenHeight()  - CGRectGetMaxY(userInfoViewframe);
    //设置一个buffer
    bottomSpace -= 40;
    CGRect keyboardRect = [noti.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    CGFloat boardHeight = keyboardRect.size.height;
    NSLog(@" keyboardWillShow editCellFrame%@ bottomSpace%f boardHeight%f", NSStringFromCGRect(userInfoViewframe), bottomSpace, boardHeight);

    CGFloat duration = [noti.userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue];
    Weakify(self);
    [UIView animateWithDuration:duration animations:^{
        Strongify(self);
        self.backView.y -= (boardHeight - bottomSpace);
    }];
    [self.tableView addGestureRecognizer:self.endEditingTap];
}