Browse Author: Savita Taware

Save and Load from KeyChain | Swift 4

import Cocoa

import Security

// see https://stackoverflow.com/a/37539998/1694526

// Arguments for the keychain queries

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, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])

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

            if (status != errSecSuccess) {

                if let err = SecCopyErrorMessageString(status, nil) {

                    print(“Read failed: \(err)”)

                }

            }

        }

    }

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

        // Instantiate a new default keychain query

        let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])

        // Delete any existing items

        let status = SecItemDelete(keychainQuery as CFDictionary)

        if (status != errSecSuccess) {

            if let err = SecCopyErrorMessageString(status, nil) {

                print(“Remove failed: \(err)”)

            }

        }

    }

    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

                if let err = SecCopyErrorMessageString(status, nil) {

                    print(“Write failed: \(err)”)

                }

            }

        }

    }

    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

    }

}

You need to imagine the following wired up to a text input field and a label, then having four buttons wired up, one for each of the methods.

class ViewController: NSViewController {

    @IBOutlet weak var enterPassword: NSTextField!

    @IBOutlet weak var retrievedPassword: NSTextField!

    let service = “myService”

    let account = “myAccount”

    // will only work after

    @IBAction func updatePassword(_ sender: Any) {

        KeychainService.updatePassword(service: service, account: account, data: enterPassword.stringValue)

    }

    @IBAction func removePassword(_ sender: Any) {

        KeychainService.removePassword(service: service, account: account)

    }

    @IBAction func passwordSet(_ sender: Any) {

        let password = enterPassword.stringValue

        KeychainService.savePassword(service: service, account: account, data: password)

    }

    @IBAction func passwordGet(_ sender: Any) {

        if let str = KeychainService.loadPassword(service: service, account: account) {

            retrievedPassword.stringValue = str

        }

        else {retrievedPassword.stringValue = “Password does not exist” }

    }

}


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