感谢 matt ！

事实证明，问题只是Xcode 11 beta 1中的一个错误，阻止了基于SwiftUI的应用程序在真实设备上进行测试.升级到Xcode 11 beta 2可以解决此问题.

It turns out the issue was just a bug in Xcode 11 beta 1, preventing SwiftUI-based apps from being testing on real devices. Upgrading to Xcode 11 beta 2 resolved the issue.