“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.

swift 3.0使用版本错误，可以选择使用之前的版本

在pods中选择相应的TARGETS将Swift Compiler -Version - Use Legacy Swift Language Version，把Unspecified改成NO。