How to uncompress a gzip file and write that out to an uncompressed file, on iPhone

I've got a file, bigfile.gz, in the bundle of my iPhone app. At app start, I want to gunzip that file to my Documents directory within my app. How can I achieve this programmatically?

Basically I want the effect of: gunzip bigfile.gz.. ob开发者_运维百科viously a gunzip utility is not available in the iOS environment though.

As pointed out in this post:

Compression API on the iPhone

both zlib and bzip2 are available. However, as another answer there points out, if you store the data for the conversations in an NSData object, then you can use an NSData category that adds gzip and zlib compression / decompression as simple methods. Here's a useful link for that.