行的子项不得包含任何 null 值，但在索引 2 处找到 null 值

Question

我有下面的屏幕图像

我在 ui 中有一个 Apple 登录，所以我只需要在 IOS 中使用这个 Apple 登录，所以我创建了以下代码：

Platform.isIOS
                                ? IPetCustomCircleBtn(
                                    constraintWidth:
                                        constraints.maxWidth * 0.13,
                                    constraintHeight:
                                        constraints.maxHeight * 0.13,
                                    iPetShapeBorder: CircleBorder(
                                      side: BorderSide(
                                        width: 2,
                                        color: Colors.black,
                                        style: BorderStyle.solid,
                                      ),
                                    ),
                                    iPetChildCard: IPetCustomIcon(
                                      ipFontIc: FontAwesomeIcons.apple,
                                      colour: Colors.black,
                                    ),
                                    iPetIconColor: Colors.black,
                                    iPetFillColor: Colors.white,
                                  )
                                : null

我发现了这个错误：

Row's children must not contain any null values, but a null value was found at index 2

我试图通过添加一个空的小部件作为下面的代码来处理这个问题

Platform.isIOS
                                ? IPetCustomCircleBtn(
                                    constraintWidth:
                                        constraints.maxWidth * 0.13,
                                    constraintHeight:
                                        constraints.maxHeight * 0.13,
                                    iPetShapeBorder: CircleBorder(
                                      side: BorderSide(
                                        width: 2,
                                        color: Colors.black,
                                        style: BorderStyle.solid,
                                      ),
                                    ),
                                    iPetChildCard: IPetCustomIcon(
                                      ipFontIc: FontAwesomeIcons.apple,
                                      colour: Colors.black,
                                    ),
                                    iPetIconColor: Colors.black,
                                    iPetFillColor: Colors.white,
                                  )
                                : SizedBox()

但问题是外观不好，因为我需要按钮的 rest 位于行的中心，这是我的全行：

Row(
                          mainAxisAlignment: MainAxisAlignment.spaceAround,
                          children: [
                            IPetCustomCircleBtn(
                              constraintWidth: constraints.maxWidth * 0.13,
                              constraintHeight: constraints.maxHeight * 0.13,
                              iPetShapeBorder: CircleBorder(),
                              iPetChildCard: IPetCustomIcon(
                                ipFontIc: FontAwesomeIcons.google,
                                colour: Colors.white,
                              ),
                              iPetIconColor: Colors.white,
                              iPetFillColor: Colors.red,
                            ),
                            IPetCustomCircleBtn(
                              constraintWidth: constraints.maxWidth * 0.13,
                              constraintHeight: constraints.maxHeight * 0.13,
                              iPetShapeBorder: CircleBorder(),
                              iPetChildCard: IPetCustomIcon(
                                ipFontIc: FontAwesomeIcons.facebook,
                                colour: Colors.white,
                              ),
                              iPetIconColor: AppConst.kPrimaryWhiteBgColor,
                              iPetFillColor: AppConst.kBlueColor,
                            ),
                            Platform.isIOS
                                ? IPetCustomCircleBtn(
                                    constraintWidth:
                                        constraints.maxWidth * 0.13,
                                    constraintHeight:
                                        constraints.maxHeight * 0.13,
                                    iPetShapeBorder: CircleBorder(
                                      side: BorderSide(
                                        width: 2,
                                        color: Colors.black,
                                        style: BorderStyle.solid,
                                      ),
                                    ),
                                    iPetChildCard: IPetCustomIcon(
                                      ipFontIc: FontAwesomeIcons.apple,
                                      colour: Colors.black,
                                    ),
                                    iPetIconColor: Colors.black,
                                    iPetFillColor: Colors.white,
                                  )
                                : SizedBox()
                          ],
                        ),

所以对于这种情况有什么好办法：D..

我希望这可以足够清楚..

Answer 1

我建议你构建两行，1 行有苹果登录，其他没有，然后调用Platform.isIOS? rowWithIos: rowWithoutIos Platform.isIOS? rowWithIos: rowWithoutIos ，如果您为所有登录类型构建小部件，您可以减少这两行中的重复代码。

Answer 2

我能想到的方法有两种：

1. 尝试为您的sizedBox 添加高度和宽度

    SizedBox(height: 0, width: 0,)

2. 尝试

    Row( mainAxisAlignment: Platform.isIOS? MainAxisAlignment.spaceAround: MainAxisAlignment.spaceBetween....

您可以根据需要替换 mainAxisAlignment

Answer 3

我找到了更好的解决方案，就像下面的代码：

if (Platform.isIOS)
                              IPetCustomCircleBtn(
                                constraintWidth: constraints.maxWidth * 0.13,
                                constraintHeight: constraints.maxHeight * 0.13,
                                iPetShapeBorder: CircleBorder(
                                  side: BorderSide(
                                    width: 2,
                                    color: Colors.black,
                                    style: BorderStyle.solid,
                                  ),
                                ),
                                iPetChildCard: IPetCustomIcon(
                                  ipFontIc: FontAwesomeIcons.apple,
                                  colour: Colors.black,
                                ),
                                iPetIconColor: Colors.black,
                                iPetFillColor: Colors.white,
                              ),