想使用NSInvocationOperation下载图片,然而并没有下载下来,
NSData为nil,
还有报错:(打断点就报错)
warning: could not load any Objective-C class information from the dyld shared cache. This will significantly reduce the quality of type information available.
现在这两个问题还没解决, 以后再看吧,先提交到git上
原文：http://www.cnblogs.com/tufei7/p/6066096.html