//接口地址

NSString*path = @"URLString";

//boundary

NSString*theBoundary =@"myBoundary";

//访问请求

NSMutableURLRequest*request = [[NSMutableURLRequestalloc]initWithURL:[NSURLURLWithString:path]];

request.HTTPMethod=@"POST";

//用来拼接参数

NSMutableData*data = [NSMutableDatadata];

//拼接第一个参数

[dataappendData:[[NSStringstringWithFormat:@"--%@\\r\\n", theBoundary]dataUsingEncoding:NSUTF8StringEncoding]];

//拼接参数名

[data appendData:[@"Content-Disposition:form-data;name=\\"uid\\"\\r\\n"dataUsingEncoding:NSUTF8StringEncoding]];

[dataappendData:[@"\\r\\n"dataUsingEncoding:NSUTF8StringEncoding]];

//拼接参数值

[dataappendData:[@"11230953"dataUsingEncoding:NSUTF8StringEncoding]];

[dataappendData:[@"\\r\\n"dataUsingEncoding:NSUTF8StringEncoding]];

//拼接第二个参数

[dataappendData:[[NSStringstringWithFormat:@"--%@\\r\\n", theBoundary]dataUsingEncoding:NSUTF8StringEncoding]];

//拼接参数名

[data appendData:[@"Content-Disposition:form-data;name=\\"file\\";filename=\\"myText.txt\\"\\r\\n"dataUsingEncoding:NSUTF8StringEncoding]];

//拼接文件类型

[dataappendData:[@"Content-Type:text/plain"dataUsingEncoding:NSUTF8StringEncoding]];

[dataappendData:[@"\\r\\n"dataUsingEncoding:NSUTF8StringEncoding]];

//拼接参数值

[dataappendData:[NSDatadataWithContentsOfFile:[[NSBundlemainBundle]pathForResource:@"myText"ofType:@"txt"]]];

[dataappendData:[@"\\r\\n"dataUsingEncoding:NSUTF8StringEncoding]];

//拼接结束标志

[dataappendData:[[NSStringstringWithFormat:@"--%@--", theBoundary]dataUsingEncoding:NSUTF8StringEncoding]];

request.HTTPBody= data;

[requestsetValue:[NSStringstringWithFormat:@"multipart/form-data;boundary=%@", theBoundary]forHTTPHeaderField:@"Content-Type"];

[requestsetValue:[NSStringstringWithFormat:@"%ld", data.length]forHTTPHeaderField:@"Content-Length"];

NSURLSession*session = [NSURLSessionsharedSession];

NSURLSessionDataTask*dataTask = [sessiondataTaskWithRequest:requestcompletionHandler:^(NSData*_Nullabledata,NSURLResponse*_Nullableresponse,NSError*_Nullableerror) {

NSDictionary*dic = [NSJSONSerializationJSONObjectWithData:dataoptions:NSJSONReadingAllowFragmentserror:nil];

NSLog(@"%@", dic);

}];

[dataTaskresume];