xcrun -sdk iphoneos clang -arch x86_64 -rewrite-objc Person+Test.m
clang -rewrite-objc -fobjc-arc -stdlib=libc++ -mmacosx-version-min=10.7 -fobjc-runtime=macosx-10.7 -Wno-deprecated-declarations keke.m
第一个里面的xcrun命令可以指定sdk
xcrun -sdk iphonesimulator clang -rewrite-objc ViewController.m
clang -rewrite-objc TestClass.m