AFNetworking HTTPRequestOperation需要从完成块设置数组但这不起作用？

I'm using AFNetworking with AFHTTPRequestOperation to pull XML data from a webservice. This is working fine and im getting the data I need but I need to split this data into objects and initialize a NSMutableArray with this data. This is working in the completion block, but just before I return the array in my method the data is gone? How do I do this?I'm using AFNetworking with AFHTTPRequestOperat