Adding Items to and Querying the iOS Keychain with Swift

I'm having trouble converting all of the Objective C code samples that are available for adding data and querying data from the iOS Keychain into Swift. I'm trying to do a basic storage of a string (an access token) and reading it back. I've had a look at some of the other questions on Stack Overflow, but I can't quite get it to work. I've tried to piece together a solution from the various sources.

Edit 1: I tried with a more basic setup, because I thought my self.defaultKeychainQuery might have been messing things up. I've updated the code below to the latest version.

Edit 2: Got it working. I wasn't adding the data value to the save query properly. I needed to convert the string to NSData. I've updated the code below to the most recent working version.

Edit 3: As Xerxes points out below, this code doesn't work with Xcode versions higher than Beta 1 because of some issue with Dictionaries. If you know of a fix for this, please let me know.

Update: I turned this into a keychain library written in Swift called Locksmith.

Save

class func save(service: NSString, data: NSString) {
  var dataFromString: NSData = data.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
  // Instantiate a new default keychain query
  var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPassword, service, userAccount, dataFromString], forKeys: [kSecClass, kSecAttrService, kSecAttrAccount, kSecValueData])

  // Delete any existing items
  SecItemDelete(keychainQuery as CFDictionaryRef)

  // Add the new keychain item
  var status: OSStatus = SecItemAdd(keychainQuery as CFDictionaryRef, nil)

  // Check that it worked ok
  println("Saving status code is: \(status)")
}

Load

  class func load(service: NSString) -> AnyObject? {
    // Instantiate a new default keychain query
    // Tell the query to return a result
    // Limit our results to one item
    var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPassword, service, userAccount, kCFBooleanTrue, kSecMatchLimitOne], forKeys: [kSecClass, kSecAttrService, kSecAttrAccount, kSecReturnData, kSecMatchLimit])



    // I'm not too sure what's happening here...
    var dataTypeRef :Unmanaged<AnyObject>?

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


    println("Loading status code is: \(status)")

    // I'm not too sure what's happening here...
    let opaque = dataTypeRef?.toOpaque()

    if let op = opaque? {
      let retrievedData = Unmanaged<NSData>.fromOpaque(op).takeUnretainedValue()
      println("Retrieved the following data from the keychain: \(retrievedData)")
      var str = NSString(data: retrievedData, encoding: NSUTF8StringEncoding)
      println("The decoded string is \(str)")
    } else {
      println("Nothing was retrieved from the keychain.")
    }

    return nil
  }

Usage (view controller)

KeychainService.saveToken("sometoken")
KeychainService.loadToken()

which uses these convenience methods

class func saveToken(token: NSString) {
    self.save("service", data: token)
  }

class func loadToken() {
    var token = self.load("service")
    if let t = token {
      println("The token is: \(t)")
    }
  }

This leads to the output in the console:

Saving status code is: 0
Loading status code is: 0
Retrieved the following data from the keychain: <736f6d65 746f6b65 6e>
The decoded string is sometoken

Thanks a lot for your help. I'm not too sure what to do with dataTypeRef once I've got it, or if it has any data given the code above.

user3927134

In order to get this to work, you will need to retrieve the retained values of the keychain constants and store then first like so:

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

You can then reference the values in the NSMutableDictionary like so:

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

I wrote a blog post about it at: http://rshelby.com/2014/08/using-swift-to-save-and-query-ios-keychain-in-xcode-beta-4/

Hope this helps!

rshelby

I wrote a demo app and helper functions for this simple task: writing/reading a text string for a given key in Keychain.

https://github.com/marketplacer/keychain-swift

let keychain = KeychainSwift()
keychain.set("hello world", forKey: "my key")
keychain.get("my key")
keychain.delete("my key")

Vitalii

My interpretation on how to add, get, delete passwords (for those who are lazy to use libraries presented in this thread):

// Saving password associated with the login and service
let userAccount = "user's login"
let service = "service name"
let passwordData: NSData = self.textfield_password.text!.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!

let keychainQuery: [NSString: NSObject] = [
        kSecClass: kSecClassGenericPassword,
        kSecAttrAccount: userAccount,
        kSecAttrService: service,
        kSecValueData: passwordData]    

SecItemDelete(keychainQuery as CFDictionaryRef) //Deletes the item just in case it already exists
let keychain_save_status: OSStatus = SecItemAdd(keychainQuery as CFDictionaryRef, nil)
print("Keychain saving code is: \(keychain_save_status)")

...

// Getting the password associated with the login and service
let userAccount = "user's login"
let service = "service name"
let keychainQuery: [NSString: NSObject] = [
    kSecClass: kSecClassGenericPassword,
    kSecAttrService: service,
    kSecAttrAccount: userAccount,
    kSecReturnData: kCFBooleanTrue,
    kSecMatchLimit: kSecMatchLimitOne]

var rawResult: AnyObject?
let keychain_get_status: OSStatus = SecItemCopyMatching(keychainQuery, &rawResult)
print("Keychain getting code is: \(keychain_get_status)")

if (keychain_get_status == errSecSuccess) {
    let retrievedData = rawResult as? NSData
    let pass = NSString(data: retrievedData!, encoding: NSUTF8StringEncoding)
    print("Username: \(userAccount), password: \(pass!)")
    // Do your work with the retrieved password here
} else {
    print("No login data found in Keychain.")

...

//Deleting user's credentials from Keychain. Password is optional for the query when you delete, in most cases you won't know it after all.
let userAccount = "user's login"
let service = "service name"

let keychainQuery: [NSString: NSObject] = [
        kSecClass: kSecClassGenericPassword,
        kSecAttrAccount: userAccount,
        kSecAttrService: service]
let keychain_delete_status: OSStatus = SecItemDelete(keychainQuery as CFDictionaryRef)
print("Keychain deleting code is: \(keychain_delete_status)")

The result codes and other useful info can be found in the official documentation: https://developer.apple.com/library/ios/documentation/Security/Reference/keychainservices/

For Swift users

Single line code to add/retrieve/update fields in Keychain:
https://github.com/jrendel/SwiftKeychainWrapper

Usage

Add a string value to keychain:

let saveSuccessful: Bool = KeychainWrapper.setString("Some String", forKey: "myKey")

Retrieve a string value from keychain:

let retrievedString: String? = KeychainWrapper.stringForKey("myKey")

Remove a string value from keychain:

let removeSuccessful: Bool = KeychainWrapper.removeObjectForKey("myKey")

matthewpalmer

I think I've worked out the solution. I've edited my post above to include the code that works (at least for me). I've also blogged about it here: using the iOS Keychain with Swift (example code).

Update 11 Aug: I've updated the code in the blog post based on rshelby's comments. Take a look.

Update: I turned this into a keychain library written in Swift called Locksmith.

Save

class func save(service: NSString, data: NSString) {
  var dataFromString: NSData = data.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
  // Instantiate a new default keychain query
  var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPassword, service, userAccount, dataFromString], forKeys: [kSecClass, kSecAttrService, kSecAttrAccount, kSecValueData])

  // Delete any existing items
  SecItemDelete(keychainQuery as CFDictionaryRef)

  // Add the new keychain item
  var status: OSStatus = SecItemAdd(keychainQuery as CFDictionaryRef, nil)

  // Check that it worked ok
  println("Saving status code is: \(status)")
}

Load

  class func load(service: NSString) -> AnyObject? {
    // Instantiate a new default keychain query
    // Tell the query to return a result
    // Limit our results to one item
    var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPassword, service, userAccount, kCFBooleanTrue, kSecMatchLimitOne], forKeys: [kSecClass, kSecAttrService, kSecAttrAccount, kSecReturnData, kSecMatchLimit])



    // I'm not too sure what's happening here...
    var dataTypeRef :Unmanaged<AnyObject>?

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


    println("Loading status code is: \(status)")

    // I'm not too sure what's happening here...
    let opaque = dataTypeRef?.toOpaque()

    if let op = opaque? {
      let retrievedData = Unmanaged<NSData>.fromOpaque(op).takeUnretainedValue()
      println("Retrieved the following data from the keychain: \(retrievedData)")
      var str = NSString(data: retrievedData, encoding: NSUTF8StringEncoding)
      println("The decoded string is \(str)")
    } else {
      println("Nothing was retrieved from the keychain.")
    }

    return nil
  }

Usage (view controller)

KeychainService.saveToken("sometoken")
KeychainService.loadToken()

which uses these convenience methods

class func saveToken(token: NSString) {
    self.save("service", data: token)
  }

class func loadToken() {
    var token = self.load("service")
    if let t = token {
      println("The token is: \(t)")
    }
  }

This leads to the output in the console:

Saving status code is: 0
Loading status code is: 0
Retrieved the following data from the keychain: <736f6d65 746f6b65 6e>
The decoded string is sometoken

来源：https://stackoverflow.com/questions/24324285/adding-items-to-and-querying-the-ios-keychain-with-swift

标签

ios

swift

local-storage

keychain