'Invalid type in JSON write (NSConcreteMutableData)'

Adding NSData into NSDirectory (JSON) getting Invalid type in JSON write (NSConcreteMutableData) error

parameter = @{@"body":@"Hi",@"image":[NSString stringWithFormat:@"%@" ,imageData]};

来源： http://stackoverflow.com/questions/15631042/adding-nsdata-into-nsdirectory-json-getting-invalid-type-in-json-write-nsconc

参考： http://www.4byte.cn/question/843610/adding-nsdata-into-nsdirectory-json-getting-invalid-type-in-json-write-nsconcretemutabledata-error.html