extensionString{

varmd5:String!{
letstr=self.cStringUsingEncoding(NSUTF8StringEncoding)
letstrLen=CC_LONG(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
letdigestLen=Int(CC_MD5_DIGEST_LENGTH)
letresult=UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)

CC_MD5(str!,strLen,result)

varhash=NSMutableString()
foriin0..<digestLen{
hash.appendFormat("%02x",result[i])
}

result.dealloc(digestLen)
returnString(format:hashasString)
}
}

写代码的时候遇到的 正好记录下

需要

#import <CommonCrypto/CommonDigest.h>