WARNING ITMS-90725: "SDK Version Issue. This app was built with the iOS 11.4 SDK. Starting March 2019, all iOS apps submitted to the App Store must be built with the iOS 12.1 SDK or later, included in Xcode 10.1 or later."
这个只是警告，从现在开始养成用 Xcode 10.1 以上的版本就行了。