将 UIImage 中的图像作为 JPEG 与其他 POST 数据一起上传 [英] Uploading an image from a UIImage as a JPEG together with other POST-data

问题描述

我正在使用此 Web 服务制作 Web 服务和 iOS 应用程序.Web 服务的 API 接受带有两个 POST 变量的 HTTP POST 请求:

I am making a web service and an iOS app using this web service. The web service's API accepts a HTTP POST request with two POST-variables:

1. picture[title]图片的标题
2. picture[picture]图片数据本身

1. picture[title] the title of the picture
2. picture[picture] the picture data itself

现在使用 HTML 这不是问题，因为 Web 浏览器会构建请求，而我唯一需要担心的是 enctype="multipart/form-data".

Now with HTML this is not a problem as the web browser constructs the request and the only thing I have to worry about is enctype="multipart/form-data".

但是对于 iOS 应用，我有两个问题，还有两个我现在要问的问题.

But with the iOS app I have two problems, together with two questions I am going to ask right now.

1. 如何将图像选择器或相机中的 UIImage 转换为原始 JPEG 数据?
2. 如何使用正确的 POST 数据创建 NSURLRequest，该数据必须包含纯文本形式的 picture[title] 字段和带有的 picture[picture] 字段JPEG数据?在服务器端，我使用 Paperclip gem，与 PHP 的 $_FILES 相当.

1. How to convert the UIImage from the image picker or camera to raw JPEG-data?
2. How to make the NSURLRequest with the right POST-data, which must contain the picture[title]-field as plain text and the picture[picture] field with the JPEG-data? On the server-side I use the Paperclip gem, comparable with PHP's $_FILES.

我见过一些上传图片的例子，但这仅包括图片，不包括其他 POST 变量.

I have seen some examples of uploading an image, but this only includes the image, not other POST-variables.

谁能帮帮我?谢谢.

推荐答案

看看这个教程，很不错:

Check out this tutorial, which is pretty nice:

http://iphone.zcentric.com/2008/08/29/post-a-uiimage-to-the-web/

有一点不太对，它把 90 作为质量设置传递给 UIImageJPEGRepresentation，它实际上将质量作为 0.0 和 1.0 之间的浮点数，所以应该是 0.9.我确信代码有效，它只是指定了 100% 的质量，而不是预期的 90%.而且，为了方便起见，万一链接中断，这里是相关代码(为了清晰和更好地适应问题而进行了重构):

One thing that's not quite right about it is that it passes 90 as a quality setting to UIImageJPEGRepresentation, which actually takes quality as a float between 0.0 and 1.0, so that should be 0.9 instead. I'm sure the code works, it's just specifying 100% quality instead of 90% as probably intended. And, just for convenience and in case that link breaks, here's the relevant code (refactored for clarity and to better fit the question):

- (void)uploadImage:(UIImage *)image toURL:(NSURL *)url withTitle:(NSString *)title {

  // encode the image as JPEG
  NSData *imageData = UIImageJPEGRepresentation(image, 0.9);

  // set up the request
  NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
  [request setURL:url];

  // create a boundary to delineate the file
  NSString *boundary = @"14737809831466499882746641449";
  // tell the server what to expect
  NSString *contentType = 
    [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
  [request addValue:contentType forHTTPHeaderField: @"Content-Type"];

  // make a buffer for the post body
  NSMutableData *body = [NSMutableData data];

  // add a boundary to show where the title starts
  [body appendData:[[NSString stringWithFormat:@"
--%@
", boundary] 
    dataUsingEncoding:NSASCIIStringEncoding]];

  // add the title
  [body appendData:[
    @"Content-Disposition: form-data; name="title"

"
    dataUsingEncoding:NSASCIIStringEncoding]];
  [body appendData:[title
    dataUsingEncoding:NSASCIIStringEncoding]];

  // add a boundary to show where the file starts
  [body appendData:[[NSString stringWithFormat:@"
--%@
", boundary] 
    dataUsingEncoding:NSASCIIStringEncoding]];

  // add a form field
  [body appendData:[
    @"Content-Disposition: form-data; name="picture"; filename="image.jpeg"
"
    dataUsingEncoding:NSASCIIStringEncoding]];

  // tell the server to expect some binary
  [body appendData:[
    @"Content-Type: application/octet-stream
"
    dataUsingEncoding:NSASCIIStringEncoding]];
  [body appendData:[
    @"Content-Transfer-Encoding: binary
"
    dataUsingEncoding:NSASCIIStringEncoding]];
  [body appendData:[[NSString stringWithFormat:
    @"Content-Length: %i

", imageData.length]
    dataUsingEncoding:NSASCIIStringEncoding]];

  // add the payload
  [body appendData:[NSData dataWithData:imageData]];

  // tell the server the payload has ended
  [body appendData:
    [[NSString stringWithFormat:@"
--%@--
", boundary] 
    dataUsingEncoding:NSASCIIStringEncoding]];

  // add the POST data as the request body
  [request setHTTPMethod:@"POST"];
  [request setHTTPBody:body];

  // now lets make the connection to the web
  NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
  NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];

  NSLog(@"%@", returnString);
}

我并没有真正编译它，因为它写在这里，所以它可能包含一些问题.

I haven't actually compiled it as it's written here, so it probably contains some issues.

在 PHP 中，您应该看到 $_REQUEST['title'] 和 $_FILES['picture'] 已设置.

In PHP, you should see that $_REQUEST['title'] and $_FILES['picture'] are set.

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