objective-c - 真机测试报错 Code=3840

Question

Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo=0x178274140 {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}
模拟器是没问题的，手机5s iOS7.0