问如何在iOS中计算SHA-2 (理想情况下是SHA256或SHA512)散列？

EN

#import <CommonCrypto/CommonDigest.h>

+ (NSData *)sha1:(NSData *)data {
    unsigned char hash[CC_SHA1_DIGEST_LENGTH];
    if ( CC_SHA1([data bytes], [data length], hash) ) {
        NSData *sha1 = [NSData dataWithBytes:hash length:CC_SHA1_DIGEST_LENGTH];        
        return sha1;
    }
return nil;
}

+ (NSString *)hashed_string:(NSString *)input
{
    const char *cstr = [input cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:input.length];
    uint8_t digest[CC_SHA256_DIGEST_LENGTH];

    // This is an iOS5-specific method.
    // It takes in the data, how much data, and then output format, which in this case is an int array.
    CC_SHA256(data.bytes, data.length, digest);

    NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH * 2];

    // Parse through the CC_SHA256 results (stored inside of digest[]).
    for(int i = 0; i < CC_SHA256_DIGEST_LENGTH; i++) {
        [output appendFormat:@"%02x", digest[i]];
    }

    return output;
}

func sha256(securityString : String) -> String {
    let data = securityString.dataUsingEncoding(NSUTF8StringEncoding)!
    var hash = [UInt8](count: Int(CC_SHA256_DIGEST_LENGTH), repeatedValue: 0)
    CC_SHA256(data.bytes, CC_LONG(data.length), &hash)
    let output = NSMutableString(capacity: Int(CC_SHA1_DIGEST_LENGTH))
    for byte in hash {
        output.appendFormat("%02x", byte)
    }
    return output as String
}