居然会自动解码，要不要这么智能，弄了快一个上午，傻逼了。。。。

1、如果不能自动解析的话，就得用http://stackoverflow.com/questions/29694050/gzip-usage-in-swift

using thisNSData+GZIP.swiftlibrary to zip/unzip data from server and here is process how to use it:

1. AddNSData+GZIP.swiftfile to your project.
2. Addlibz.dyliblibrary to your project.
3. Add a line#include <zlib.h>to yourProjectName-Bridging-Header.hfile.
4. Invoke from your Swift/ObjC files.

2、如果你和我情况一样，加一行代码就搞定了：

request.addValue("Accept-Encoding",forHTTPHeaderField:"gzip")

例如：

let request :NSMutableURLRequest = NSMutableURLRequest(URL: URL,cachePolicy: NSURLRequestCachePolicy.UseProtocolCachePolicy,timeoutInterval: 40)
request.HTTPMethod = "GET"
request.addValue("Accept-Encoding",forHTTPHeaderField: "gzip")

NSURLConnection.sendAsynchronousRequest(request,queue: NSOperationQueue.mainQueue(),completionHandler:
{(response :NSURLResponse?,data: NSData?,error: NSError?) -> Void in
    callback(error,data)
})