AFNetworking form 表单上传图片的问题

afnetworking 上传图片，后台接受不到参数，无奈之下，参数拼在了url之后，图片成功上传 ，首先给有同样困惑的人一个解决方法，同是求问，放在请求体参数中为什么不行？？
下面上代码
//处理拼接后的特殊字符处理

     NSString *encodedString = (NSString *)     CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault， (CFStringRef)jsonstring,  NULL, (CFStringRef)@"!*'();:@&=+$,/?%#[]",  kCFStringEncodingUTF8));
        NSString *str = [NSString stringWithFormat:@"%@?auth=%@&token=%@",exChangeHeadeImage,encodedString,token];
        AFHTTPSessionManager *manager = [Manager sharedHTTPSession];
        manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json",
                                                             @"text/html",
                                                             @"text/plain",
                                                             @"image/jpeg",
                                                             @"image/png",
                                                             @"application/octet-stream",
                                                             @"text/json",
                                                             nil];
        [manager POST:str parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData>  _Nonnull formData) {
                [formData appendPartWithFileData:UIImageJPEGRepresentation(image, 0.3) name:@"file" fileName:@"123.jpg" mimeType:@"image/jpg"];
        } progress:^(NSProgress * _Nonnull uploadProgress) {
        } success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
            NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:responseObject options:NSJSONReadingMutableContainers error:nil];
            KKLog(@"%@",dict)；  
        } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) { 
        }];