Use Legacy Swift Language Version” (SWIFT_VERSION) is required to be configured correctly for targets which use Swift. Use the [Edit > Convert > To Current Swift Syntax…] menu to choose a Swift version or use the Build Settings editor to configure the build setting directly.
QQ20170629-161834@2x.png
解决方法：
Build settings -> search swift, choice use legacy swift language version
Toggled no to yes -> build. You will get more error.
Back toggled yes to no. build -> success!
上图：
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