HTTP POST and Multipart forms.md

HTTP POST And Multipart Forms

参考资料：

• Sending Multipart Forms with Objective-C
• POST multipart/form-data with Objective-C
• Sending an HTTP POST request on iOS
• The Multipart Content-Type--w3规范

注意事项：

• http Body 中的NSData 编码方式要用NSASCIIStringEncoding而不是NSUTF8StringEncoding

• 通过

  NSString *postLength = [NSString stringWithFormat:@"%d",[postData length]]; 计算数据的长度

POST参数设置

		//设置header Content-Length
		[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
		//设置header contentType
		[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Current-Type"];
		//设置body
		[request setHTTPBody:postData];

备注:普通post的header的Current-Type为application/x-www-form-urlencoded

Multipart Forms POST参数设置

		//设置header contentType
		NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
		[request addValue:contentType forHTTPHeaderField:@"Content-Type"];

		//设置body contentType
		[body appendData:[@"Content-Type: application/octet-stream\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];

备注:Multipart Forms的header的Current-Type为multipart/form-data

request body like this

	--YOUR_BOUNDARY_STRING
	Content-Disposition: form-data; name="photo"; filename="calm.jpg"
	Content-Type: image/jpeg

	YOUR_IMAGE_DATA_GOES_HERE
	--YOUR_BOUNDARY_STRING
	Content-Disposition: form-data; name="message"

	My first message
	--YOUR_BOUNDARY_STRING
	Content-Disposition: form-data; name="user"

	1
	--YOUR_BOUNDARY_STRING

I’m sending over three variables: an image named photo, a string named message, and an integer named user. It’s important to note the linebreaks and the dashes before the boundary string. These must be included in order to build a good request. Now lets write some objective-c:

	NSString *boundary = @"YOUR_BOUNDARY_STRING";
	NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
	[request addValue:contentType forHTTPHeaderField:@"Content-Type"];
	
	NSMutableData *body = [NSMutableData data];
	
	[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
	[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"photo\"; filename=\"%@.jpg\"\r\n", self.message.photoKey] dataUsingEncoding:NSUTF8StringEncoding]];
	[body appendData:[@"Content-Type: application/octet-stream\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
	[body appendData:[NSData dataWithData:imageData]];
	
	[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
	[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"message\"\r\n\r\n%@", self.message.message] dataUsingEncoding:NSUTF8StringEncoding]];
	
	[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
	[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"user\"\r\n\r\n%d", 1] dataUsingEncoding:NSUTF8StringEncoding]];
	
	[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
	
	[request setHTTPBody:body];

Now all we need to do is make a connection to the server and send the request:

[request setHTTPBody:body];

	NSURLResponse *response;
	NSError *error;
	
	[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];

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