ios SHA1WithRSA加密

[m0_37337907]

请问下边安卓代码 翻译成ios代码要怎么写 有大神帮一下呗
/**
* 用私钥对信息生成数字签名
* @param content 加密数据
* @param privateKey 私钥
* @return
* @throws Exception
*/
public static String sign(Map<String, String> content, String privateKey)throws Exception{
try {
/** 生成私钥 */
// 解密私钥
byte[] keyBytes = Coder.decryptBASE64(privateKey);
//构造PKCS8EncodedKeySpec对象
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(keyBytes);
// 指定加密算法
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORTHM);
// 取私钥匙对象
PrivateKey privateKey2 = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
// 用私钥对信息生成数字签名
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initSign(privateKey2);
signature.update(getSigningStr(content).getBytes());
byte[] signed = signature.sign();
return new String(Base64.encodeBase64(signed, false));
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException("无此算法", e);
} catch (SignatureException e) {
throw new RuntimeException("签名异常", e);
} catch (InvalidKeyException e) {
throw new RuntimeException("私钥非法", e);
}
}