base64 HmacSHA1 decode in iPhone

I am working on an iPhone application that requires Base64开发者_如何学Go decoding using HmacSHA1 algorithm. Can anyone help me doing the objective-C equivalent of the given Java code:

SecretKeykey = new SecretKeySpec(com.sinotar.algorithm.Base64.decode(
    "vNQKX3C1wD/KprnnOcdRwM80YIn5bo47w9VdTlDpCB8="), "HmacSHA1");

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Thanks matthijz, But it has nothing to do with HmacSHA1. The solution I am looking for is something that does the equivalent of the Java code:

SecretKey key = null; 
try { key = new SecretKeySpec(com.sinotar.algorithm.Base64.decode("vNQKX3C1wD/KprnnOcdRwM80YIn5bo47w9VdTlDpCB8="), 
                              "HmacSHA1"); 
} 

Any help is appreciated.

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Check out Matt Gallagher's article on Base64 encoding - it has downloadable code at the end. http://cocoawithlove.com/2009/06/base64-encoding-options-on-mac-and.html

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The code you quote appears to be taking a base64 value, converting it to binary, and using it to set the key for an HMACSHA1 algorithm. The two steps are conceptually separate.

Here is the page for HMAC_SHA1 on Mac -- I haven't found the equivalent for iPhone, but I would assume it exists.