如何在没有任何第三方库的情况下使用钥匙串在swift 4中存储敏感数据

Question

我想在swift 4中使用Keychain来存储登录时的用户ID等敏感数据，并希望检查是否存在或每次用户再次打开此应用时。

我也不想使用第三方库。

我正在使用这种方法。好吗？

    let kSecClassValue = NSString(format: kSecClass)
    let kSecAttrAccountValue = NSString(format: kSecAttrAccount)
    let kSecValueDataValue = NSString(format: kSecValueData)
    let kSecClassGenericPasswordValue = NSString(format: kSecClassGenericPassword)
    let kSecAttrServiceValue = NSString(format: kSecAttrService)
    let kSecMatchLimitValue = NSString(format: kSecMatchLimit)
    let kSecReturnDataValue = NSString(format: kSecReturnData)
    let kSecMatchLimitOneValue = NSString(format: kSecMatchLimitOne)

    public class KeychainService: NSObject {

    class func updatePassword(service: String, account:String, data: String) {
        if let dataFromString: Data = data.data(using: String.Encoding.utf8, allowLossyConversion: false) {

            // Instantiate a new default keychain query
            let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue])

            let status = SecItemUpdate(keychainQuery as CFDictionary, [kSecValueDataValue:dataFromString] as CFDictionary)

            if (status != errSecSuccess) {
                print("Read failed: \(status)")
            }
        }
    }


    class func removePassword(service: String, account:String) {

        // Instantiate a new default keychain query
        let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue])

        // Delete any existing items
        let status = SecItemDelete(keychainQuery as CFDictionary)
        if (status != errSecSuccess) {
            print("Remove failed: \(status)")
        }

    }


    class func savePassword(service: String, account:String, data: String) {
        if let dataFromString = data.data(using: String.Encoding.utf8, allowLossyConversion: false) {

            // Instantiate a new default keychain query
            let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account, dataFromString], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecValueDataValue])

            // Add the new keychain item
            let status = SecItemAdd(keychainQuery as CFDictionary, nil)

            if (status != errSecSuccess) {    // Always check the status
                print("Write failed: \(status)")
            }
        }
    }

    class func loadPassword(service: String, account:String) -> String? {
        // Instantiate a new default keychain query
        // Tell the query to return a result
        // Limit our results to one item
        let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])

        var dataTypeRef :AnyObject?

        // Search for the keychain items
        let status: OSStatus = SecItemCopyMatching(keychainQuery, &dataTypeRef)
        var contentsOfKeychain: String?

        if status == errSecSuccess {
            if let retrievedData = dataTypeRef as? Data {
                contentsOfKeychain = String(data: retrievedData, encoding: String.Encoding.utf8)
            }
        } else {
            print("Nothing was retrieved from the keychain. Status code \(status)")
        }
        return contentsOfKeychain
    }
}

我删除了两个密钥对values(kSecReturnDataValue, kSecMatchLimitValue)