使用Objective-C POST多部分/表单数据

Question

所以这个HTML代码为我提交了正确格式的数据.

<form action="https://www.example.com/register.php" method="post" enctype="multipart/form-data">
    Name: <input type="text" name="userName"><BR />
    Email: <input type="text" name="userEmail"><BR />
    Password: <input type="text" name="userPassword"><BR />
    Avatar: <input type="file" name="avatar"><BR />
    <input type="submit">
</form>

我已经查看过很多关于如何在iOS上进行multipart/form-data POST的文章,但没有一篇真正解释如果有正常的参数以及文件上传怎么办.

你能帮我解决一下在Obj-C中发帖的代码吗？

谢谢!

Answer 1

过程如下:

1. 创建字典的userName,userEmail和userPassword参数.

   NSDictionary *params = @{@"userName"     : @"rob",
                            @"userEmail"    : @"rob@email.com",
                            @"userPassword" : @"password"};
   

2. 确定图像的路径:

   NSString *path = [[NSBundle mainBundle] pathForResource:@"avatar" ofType:@"png"];
   

3. 创建请求:

   NSString *boundary = [self generateBoundaryString];
   
   // configure the request
   
   NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
   [request setHTTPMethod:@"POST"];
   
   // set content type
   
   NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
   [request setValue:contentType forHTTPHeaderField: @"Content-Type"];
   
   // create body
   
   NSData *httpBody = [self createBodyWithBoundary:boundary parameters:params paths:@[path] fieldName:fieldName];
   

4. 这是上面用于构建请求主体的方法:

   - (NSData *)createBodyWithBoundary:(NSString *)boundary
                           parameters:(NSDictionary *)parameters
                                paths:(NSArray *)paths
                            fieldName:(NSString *)fieldName {
       NSMutableData *httpBody = [NSMutableData data];
   
       // add params (all params are strings)
   
       [parameters enumerateKeysAndObjectsUsingBlock:^(NSString *parameterKey, NSString *parameterValue, BOOL *stop) {
           [httpBody appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
           [httpBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n\r\n", parameterKey] dataUsingEncoding:NSUTF8StringEncoding]];
           [httpBody appendData:[[NSString stringWithFormat:@"%@\r\n", parameterValue] dataUsingEncoding:NSUTF8StringEncoding]];
       }];
   
       // add image data
   
       for (NSString *path in paths) {
           NSString *filename  = [path lastPathComponent];
           NSData   *data      = [NSData dataWithContentsOfFile:path];
           NSString *mimetype  = [self mimeTypeForPath:path];
   
           [httpBody appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
           [httpBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"; filename=\"%@\"\r\n", fieldName, filename] dataUsingEncoding:NSUTF8StringEncoding]];
           [httpBody appendData:[[NSString stringWithFormat:@"Content-Type: %@\r\n\r\n", mimetype] dataUsingEncoding:NSUTF8StringEncoding]];
           [httpBody appendData:data];
           [httpBody appendData:[@"\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
       }
   
       [httpBody appendData:[[NSString stringWithFormat:@"--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
   
       return httpBody;
   }
   

5. 以上使用以下实用方法:

   @import MobileCoreServices;    // only needed in iOS
   
   - (NSString *)mimeTypeForPath:(NSString *)path {
       // get a mime type for an extension using MobileCoreServices.framework
   
       CFStringRef extension = (__bridge CFStringRef)[path pathExtension];
       CFStringRef UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, extension, NULL);
       assert(UTI != NULL);
   
       NSString *mimetype = CFBridgingRelease(UTTypeCopyPreferredTagWithClass(UTI, kUTTagClassMIMEType));
       assert(mimetype != NULL);
   
       CFRelease(UTI);
   
       return mimetype;
   }
   
   - (NSString *)generateBoundaryString {
       return [NSString stringWithFormat:@"Boundary-%@", [[NSUUID UUID] UUIDString]];
   }
   

6. 然后提交请求.这里有很多很多选择.

   例如,如果使用NSURLSession,您可以创建NSURLSessionUploadTask:

   NSURLSession *session = [NSURLSession sharedSession];  // use sharedSession or create your own
   
   NSURLSessionTask *task = [session uploadTaskWithRequest:request fromData:httpBody completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
       if (error) {
           NSLog(@"error = %@", error);
           return;
       }
   
       NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
       NSLog(@"result = %@", result);
   }];
   [task resume];
   

   或者你可以创建一个NSURLSessionDataTask:

   request.HTTPBody = httpBody;
   
   NSURLSessionTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
       if (error) {
           NSLog(@"error = %@", error);
           return;
       }
   
       NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
       NSLog(@"result = %@", result);
   }];
   [task resume];
   

   以上假设服务器只是返回文本响应.如果服务器返回JSON更好,在这种情况下你使用NSJSONSerialization而不是NSString方法initWithData.

   同样,我正在使用上面的完成块再现NSURLSession,但也可以使用更丰富的基于委托的再现.但这似乎超出了这个问题的范围,所以我会把它留给你.

但希望这说明了这个想法.

如果我没有指出这一点,比上面容易得多,你可以使用AFNetworking,重复上面的步骤1和2,然后只是调用:

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.responseSerializer = [AFHTTPResponseSerializer serializer]; // only needed if the server is not returning JSON; if web service returns JSON, remove this line
NSURLSessionTask *task = [manager POST:urlString parameters:params constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
    NSError *error;
    if (![formData appendPartWithFileURL:[NSURL fileURLWithPath:path] name:@"avatar" fileName:[path lastPathComponent] mimeType:@"image/png" error:&error]) {
        NSLog(@"error appending part: %@", error);
    }
}  progress:nil success:^(NSURLSessionTask *task, id responseObject) {
    NSLog(@"responseObject = %@", responseObject);
} failure:^(NSURLSessionTask *task, NSError *error) {
    NSLog(@"error = %@", error);
}];

if (!task) {
    NSLog(@"Creation of task failed.");
}