选择项目设置并转到TARGETS。单击Watch Kit应用程序，选择Build Settings。对于关键的iOS部署目标，您应该找到iOS 8.3。出于某种原因，Xcode 6.3 Beta 4希望在iOS 8.2上使用Debug和Release。现在你的项目应按预期进行构建。

Select your project settings and go to "TARGETS". Click on your Watch Kit App, select Build Settings. For the key "iOS Deployment Target" you should find "iOS 8.3". For some reason Xcode 6.3 Beta 4 wants to have this on "iOS 8.2" for "Debug" and "Release". Now your project should build as expected.

对于XCODE 6.3版本，这仍然是正确的！

This is still true for XCODE 6.3 release!