小编Pau*_*Cbt的帖子

刚刚在渠道稳定版上升级到 flutter 3.7.3。在 ios 模拟器上运行效果很好，但是当我尝试存档项目时：

Failed to build iOS app\nError (Xcode): Expected Flutter 857bd6b74c5eb56151bfafe91e7fa6a82b6fee25, but found 248290d6d50a1bf1a6a246544347c03acda867a5\n\n\nEncountered error while archiving for device.\n

颤振医生是：

Doctor summary (to see all details, run flutter doctor -v):\n[\xe2\x9c\x93] Flutter (Channel stable, 3.7.3, on macOS 13.0 22A380 darwin-arm64, locale fr-FR)\n[!] Android toolchain - develop for Android devices (Android SDK version 33.0.0)\n    \xe2\x9c\x97 cmdline-tools component is missing\n      Run `path/to/sdkmanager --install "cmdline-tools;latest"`\n      See https://developer.android.com/studio/command-line for more details.\n    \xe2\x9c\x97 Android license status unknown.\n      Run `flutter doctor …

两者之间到底有什么区别

String id = folderInfo!.first.id;   //this works

和

String id = folderInfo?.first.id; //this is an error

我知道 ？。当值对象为 null 时返回 null，但是 !. 返回？