当我输入swift build时，输出为
error: system(["/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2016-06-06-a.xctoolchain/usr/bin/swiftc", "--driver-mode=swift", "-I", "/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2016-06-06-a.xctoolchain/usr/lib/swift/pm", "-L", "/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2016-06-06-a.xctoolchain/usr/lib/swift/pm", "-lPackageDescription", "-target", "x86_64-apple-macosx10.10", "/Users/weichuang/Desktop/perfect/hello/Package.swift", "-fileno", "4"], posix_spawn error: No such file or directory (2), `["/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2016-06-06-a.xctoolchain/usr/bin/swiftc", "--driver-mode=swift", "-I", "/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2016-06-06-a.xctoolchain/usr/lib/swift/pm", "-L", "/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2016-06-06-a.xctoolchain/usr/lib/swift/pm", "-lPackageDescription", "-target", "x86_64-apple-macosx10.10", "/Users/weichuang/Desktop/perfect/hello/Package.swift", "-fileno", "4"]`)
我的mac是OS X EI，我的Xcode是7.3，如何解决？