包含桥接头文件

#import <CommonCrypto/CommonDigest.h>

extension String{ func md5() -> String! { let str = self.cStringUsingEncoding(NSUTF8StringEncoding) let strLen = CUnsignedInt(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding)) let digestLen = Int(CC_MD5_DIGEST_LENGTH) let result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen) CC_MD5(str!,strLen,result) let hash = NSMutableString() for i in 0 ..< digestLen { hash.appendFormat("%02x",result[i]) } result.destroy() return String(format: hash as String) }}