在網絡編程中，如果需要上傳圖片，那么他的方法將會和普通的上傳數據不同，下面將講解如何上傳圖片。

環境信息：

Mac OS X 10.9.5

Xcode 5.1.1

IOS 7.1

正文：

- (NSURLRequest *)configPostImageURLWithMethod:(NSString *)method parameters:(NSDictionary *)parameters {
    
    NSString *TWITTERFON_FORM_BOUNDARY = @"AaB03x";
    //根據url初始化request
    NSMutableURLRequest* request = [NSMutableURLRequestrequestWithURL:[NSURLURLWithString:method]
                                                           cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                                                       timeoutInterval:10];
    
    NSString *boundary = [NSStringstringWithFormat:@"--%@",TWITTERFON_FORM_BOUNDARY];
    
    NSString *endMPboundary = [NSStringstringWithFormat:@"%@--",boundary];
    //要上傳的圖片
    UIImage *image = [parameters objectForKey:@"pic"];
    //得到圖片的data
    NSData* data = UIImagePNGRepresentation(image);
    //http body的字符串
    NSMutableString *body = [NSMutableStringstring];
    //參數的集合的所有key的集合
    NSArray *keys = [parameters allKeys];
    
    //遍歷keys
    for (int i = 0; i < [keys count]; i ++) {
        
        //得到當前key
        NSString *key = [keys objectAtIndex:i];
        //如果key不是pic，說明value是字符類型，比如name：Boris
        if (![key isEqualToString:@"pic"])
        {
            //添加分界線，換行
            [body appendFormat:@"%@\r\n", boundary];
            //添加字段名稱，換2行
            [body appendFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n\r\n", key];
            //添加字段的值
            [body appendFormat:@"%@\r\n", [parameters objectForKey:key]];
        }
    }
    
    //添加分界線，換行
    [body appendFormat:@"%@\r\n", boundary];
    //聲明pic字段，文件名為boris.png
    [body appendFormat:@"Content-Disposition: form-data; name=\"pic\"; filename=\"boris.png\"\r\n"];
    //聲明上傳文件的格式
    [body appendFormat:@"Content-Type: image/png\r\n\r\n"];
    
    //聲明結束符：--AaB03x--
    NSString *end = [NSStringstringWithFormat:@"\r\n%@",endMPboundary];
    //聲明myRequestData，用來放入http body
    NSMutableData *myRequestData = [NSMutableDatadata];
    //將body字符串轉化為UTF8格式的二進制
    [myRequestData appendData:[body dataUsingEncoding:NSUTF8StringEncoding]];
    //將image的data加入
    [myRequestData appendData:data];
    //加入結束符--AaB03x--
    [myRequestData appendData:[end dataUsingEncoding:NSUTF8StringEncoding]];
    
    //設置HTTPHeader中Content-Type的值
    NSString *content = [NSStringstringWithFormat:@"multipart/form-data; boundary=%@",TWITTERFON_FORM_BOUNDARY];
    //設置HTTPHeader
    [request setValue:content forHTTPHeaderField:@"Content-Type"];
    //設置Content-Length
    [request setValue:[NSStringstringWithFormat:@"%d", [myRequestData length]] forHTTPHeaderField:@"Content-Length"];
    //設置http body
    [request setHTTPBody:myRequestData];
    //http method
    [request setHTTPMethod:@"POST"];
    
    return request;
}

注：在使用這個方法的時候，圖片的key必須是pic。