1、#import "AFHTTPSessionManager.h"

2、    //网络请求管理器

    AFHTTPSessionManager *sessionManager = [AFHTTPSessionManager manager];

3、 //设置请求内容的类型

//重中之重：添加header前先初始化AFJSONRequestSerializer，否则无法添加

    sessionManager.requestSerializer = [AFJSONRequestSerializer new];

    [sessionManager.requestSerializer setValue:@"application/json;charset=utf-8" forHTTPHeaderField:@"content-type"];

    [sessionManager.requestSerializer setValue:@"text/xml,application/json" forHTTPHeaderField:@"Accept"];

    [sessionManager.requestSerializer setValue:@"zh-CN,zh;q=0.8" forHTTPHeaderField:@"Accept-Language"];

    [sessionManager.requestSerializer setValue:@"Keep-Alive" forHTTPHeaderField:@"Connection"];

    [sessionManager.requestSerializer setValue:@"WLJY-ANDROID" forHTTPHeaderField:@"client-type"];

    [sessionManager.requestSerializer setValue:@"identity" forHTTPHeaderField:@"Accept-Encoding"];

4、

[sessionManager POST:requestUrlStr parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData>  _Nonnull formData) {

          //发送内容 （NSData到后台即是file类型）下面举例上传一次多张图片，array即图片数组

    for(int i =0; i< array.count ; i++){

            NSData*imageData = （图片转NSData 自己查 取单张图片array[i]）

            NSDateFormatter *formatter = [[NSDateFormatter alloc] init];

            formatter.dateFormat=@"yyyyMMddHHmmss";

            NSString*str = [formatter  stringFromDate:[NSDatedate]];

            NSString*fileName = [NSString  stringWithFormat:@"%@.jpg", str];

            [formData  appendPartWithFileData:imageData  name:@"img"  fileName:fileName  mimeType:@"multipart/form-data"];

        }

    }progress:^(NSProgress*_NonnulluploadProgress) {

        nil;

    }success:^(NSURLSessionDataTask*_Nonnulltask,id  _NullableresponseObject) {

        NSLog(@"success");

    }failure:^(NSURLSessionDataTask*_Nullabletask,NSError*_Nonnullerror) {

        NSLog(@"default");

    }];

}