Class-dump: class-dump-x和class-dump-z如何分析dylib等文件？

LZXdeMac:~ lzx$ class-dump --arch x86_64 -H /Users/lzx/Desktop/Optimizely-iOS-SDK-master/Optimizely.framework/Versions/A/Optimizely -o /Users/optimizelyheads
Error: Fat file doesn't contain a valid Mach-O file for the specified architecture (x86_64). It probably means that class-dump was run on a static library, which is not supported.
我加了--arch 。。。但是还是报错，是为什么？求大神赐教