clang -x objective-c -rewrite-objc -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator10.3.sdkMyClassTest.m
//支持weak
clang -x objective-c -rewrite-objc -fobjc-arc -fblocks -mios-version-min=8.0.0 -fobjc-runtime=ios-8.0.0 -O0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk clang.m
