记一次flutter 报错:CocoaPods could not find compatible versions for pod

[!] CocoaPods could not find compatible versions for pod "Firebase/Auth":
In snapshot (Podfile.lock):
Firebase/Auth (= 11.8.0)

In Podfile:
firebase_auth (from .symlinks/plugins/firebase_auth/ios) was resolved to 5.6.2, which depends on
Firebase/Auth (= 11.15.0)

Specs satisfying the Firebase/Auth (= 11.8.0), Firebase/Auth (= 11.15.0) dependency were found, but they required a higher minimum deployment target.

以上的问题是在flutter for ios的工程中，加入flutter crashlytics这个库时出现的报错，原因是当前本地的cocoapods中没有Firebase/Auth的11.15.0版本的spec，所以需要我们升级。

这个问题在flutter pub get或者flutter add xxx时没有出现，但是在编译到iOS设备中时会出现。

所以一般我会在flutter pub get后，再cd到iOS目录中执行pod install

解决上面截图中的办法就是要更新本地cocoapods spec：

pod install --repo-update --verbose

这样就可以了