I also tried exporting without alpha it did not work for me but I figured it out that why I was getting error. I create an AppIcon using Figma & Sketch, but I tried to make a 2D geometry shape to 3D viewable. So I assume that I can achieve it by using some shadows & the same geometry but with lower alpha-like %70. After that, I got the AppIcon and export it without Alpha ticking but the problem was the main source of the image includes a container with lower alpha-like I did. So I change it to another graphical shape without alpha and it worked.

I also tried exporting without alpha it did not work for me but I figured it out that why I was getting error. I create an AppIcon using Figma & Sketch, but I tried to make a 2D geometry shape to 3D viewable. So I assume that I can achieve it by using some shadows & the same geometry but with lower alpha-like %70. After that, I got the AppIcon and export it without Alpha ticking but the problem was the main source of the image includes a container with lower alpha-like I did. So I change it to another graphical shape without alpha and it worked.

我可以通过复制文件来解决Mac Sierra OS的问题，将新文件拖到桌面上，在预览中打开，然后单击导出选项(在文件菜单中)，然后出现不带“alpha”的保存选项

错误信息本身是这样的:

“无效的应用商店图标。在资产目录中的应用程序商店图标 “YourApp。应用不能透明，也不能包含alpha通道。”

所有应用程序图标必须是方形的，不透明或半透明(alpha值!= 1.0)。

提示:应用程序图标可能有圆角。(在这里分享你的应用程序图标)

以下是苹果应用程序图标-人机界面指南

这里有一个解决方案，对我在High Sierra工作

在预览应用程序(默认的OSX图像查看器)中打开应用商店图标(1024*1024)。 从菜单栏单击“文件”菜单并选择“导出”。 查看截图 取消选中Alpha，选择您想要导出图像的位置，然后单击保存按钮。查看截图 将当前的App Store图标替换为新导出的图标图像。 验证并上传。

从这里生成应用程序图标https://appicon.co/ 删除资产。Xcassets文件(project->ios->runner) 复制的资产。Xcassets从新生成的图标文件夹和过去这里(项目->ios->runner) 从XCode执行干净的构建文件夹 然后存档并上传新的构建