1.随便新建一个OC文件会提示新建桥接文件xxx-Bridging-Header.

2.在桥接文件加入#import <CommonCrypto/CommonDigest.h>

3.新增一个swift文件StringMd5.swift

4.在StringMd5.swift加入

extension String {    func md5() -> String {        let str = self.cString(using: String.Encoding.utf8)        let strLen = CUnsignedInt(self.lengthOfBytes(using: String.Encoding.utf8))        let digestLen = Int(CC_MD5_DIGEST_LENGTH)        let result = UnsafeMutablePointer.allocate(capacity: digestLen)

CC_MD5(str!, strLen, result)

let hash = NSMutableString()

for i in 0 ..< digestLen {

hash.appendFormat("%02x", result[i])

}

result.deinitialize()

return String(format: hash as String)

}

}

5.调用方法为String类字符串.md5()