Fix JSON serialization bug
Fix JSON serialization bug

Handle case where result is an NSDictionary, don't assume
result is always an NSString.

respoke/respoke-sdk-ios,i-miss-you/respoke-sdk-ios,respoke/respoke-sdk-ios,Havi4/respoke-sdk-ios,i-miss-you/respoke-sdk-ios,JeeLiu/respoke-sdk-ios,respoke/respoke-sdk-ios,Havi4/respoke-sdk-ios,iosyoujian/respoke-sdk-ios,JeeLiu/respoke-sdk-ios,Havi4/respoke-sdk-ios,iosyoujian/respoke-sdk-ios,JeeLiu/respoke-sdk-ios,i-miss-you/respoke-sdk-ios,iosyoujian/respoke-sdk-ios