与后台返回数据类型老是出错（文档和现实老是对接不上）

[__NSCFNumber length]: unrecognized selector sent to instance 0x1657c5c0

2014-09-24 14:47:39.170 StarShow[1948:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFNumber length]: unrecognized selector sent to instance 0x1657c5c0'

*** First throw call stack:

错误原因：服务器那边传过来的是int类型的，我这边定义的对象的作品这个属性是string类型的。与后台返回数据类型老是出错（文档和现实老是对接不上）

 hot.showWorks= [NSStringstringWithFormat:
                                     @"%@",[dictionary objectForKey:@"worknum"]];//Int作品数