您可能正在使用免费的开发者帐户.Apple 在 13.3.1 升级后阻止在免费帐户上使用外部框架.如果仍有可能，请尝试降级到 13.3 或购买 Apple 开发者许可证.

You are probably using free developer account. Apple blocked utilizing external frameworks on free accounts with 13.3.1 upgrade. Try downgrading to 13.3 if still possible or buy Apple Developer License.

更新 04/2020:升级到 iOS 13.4 和 XCode 11.4 目前解决了这个问题.

UPDATE 04/2020: Upgrading to iOS 13.4 and XCode 11.4 currently solves this issue.