文件的上传

- (void)upload
{
    //1.确定请求路径
    NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/upload"];

    //2.创建一个可变的请求对象
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

    //3.设置请求方式为POST
    request.HTTPMethod = @"POST";

    //4.设置请求头
    NSString *filed = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",Kboundary];
    [request setValue:filed forHTTPHeaderField:@"Content-Type"];

    //5.设置请求体
    NSMutableData *data = [NSMutableData data];
    //5.1 文件参数
    /*
     --分隔符
     Content-Disposition:参数
     Content-Type:参数
     空行
     文件参数
     */
    [data appendData:[[NSString stringWithFormat:@"--%@",Kboundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [data appendData:KnewLine];
    [data appendData:[@"Content-Disposition: form-data; name=\"file\"; filename=\"test.png\"" dataUsingEncoding:NSUTF8StringEncoding]];
    [data appendData:KnewLine];
    [data appendData:[@"Content-Type: image/png" dataUsingEncoding:NSUTF8StringEncoding]];
    [data appendData:KnewLine];
    [data appendData:KnewLine];
    [data appendData:KnewLine];

    UIImage *image = [UIImage imageNamed:@"test"];
    NSData *imageData = UIImagePNGRepresentation(image);
    [data appendData:imageData];
    [data appendData:KnewLine];

    //5.2 非文件参数
    /*
     --分隔符
     Content-Disposition:参数
     空行
     非文件参数的二进制数据
     */

    [data appendData:[[NSString stringWithFormat:@"--%@",Kboundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [data appendData:KnewLine];
    [data appendData:[@"Content-Disposition: form-data; name=\"username\"" dataUsingEncoding:NSUTF8StringEncoding]];
    [data appendData:KnewLine];
    [data appendData:KnewLine];
    [data appendData:KnewLine];

    NSData *nameData = [@"wendingding" dataUsingEncoding:NSUTF8StringEncoding];
    [data appendData:nameData];
    [data appendData:KnewLine];

    //5.3 结尾标识
    //--分隔符--
    [data appendData:[[NSString stringWithFormat:@"--%@--",Kboundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [data appendData:KnewLine];

    request.HTTPBody = data;

    //6.发送请求
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * __nullable response, NSData * __nullable data, NSError * __nullable connectionError) {

        //7.解析服务器返回的数据
        NSLog(@"%@",[NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil]);
    }];
}

//如果想要及时拿到该数据，那么可以发送一个同步请求
- (NSString *)getMIMEType
{
    NSString *filePath = @"/Users/HMJ/Desktop/备课/其它/swift.md";

    NSURLResponse *response = nil;
    [NSURLConnection sendSynchronousRequest:[NSURLRequest requestWithURL:[NSURL fileURLWithPath:filePath]] returningResponse:&response error:nil];
    return response.MIMEType;
}

//对该文件发送一个异步请求，拿到文件的MIMEType
- (void)MIMEType
{

    //    NSString *file = @"file:///Users/HMJ/Desktop/test.png";

    [NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:[NSURL fileURLWithPath:@"/Users/HMJ/Desktop/test.png"]] queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * __nullable response, NSData * __nullable data, NSError * __nullable connectionError) {
        //       response.MIMEType
        NSLog(@"%@",response.MIMEType);

    }];
}

//注意：需要依赖于框架MobileCoreServices
- (NSString *)mimeTypeForFileAtPath:(NSString *)path
{
    if (![[[NSFileManager alloc] init] fileExistsAtPath:path]) {
        return nil;
    }

    CFStringRef UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)[path pathExtension], NULL);
    CFStringRef MIMEType = UTTypeCopyPreferredTagWithClass (UTI, kUTTagClassMIMEType);
    CFRelease(UTI);
    if (!MIMEType) {
        return @"application/octet-stream";
    }
    return (__bridge NSString *)(MIMEType);
}