Swift Keychain Class

KeychainService.swift

import UIKit
import Security

let serviceIdentifier = "com.company"
let accessGroup = "com.company.app"

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

class KeychainService: NSObject {
    class func setString(value: NSString, forKey: String) {
        self.save(serviceIdentifier, key: forKey, data: value)
    }
    
    class func stringForKey(key: String) -> NSString? {
        var token = self.load(serviceIdentifier, key: key)
        
        return token
    }

    class func removeItemForKey(key: String) {
        self.save(serviceIdentifier, key: key, data: "")
    }
    
    class func save(service: NSString, key: String, data: NSString) {
        var dataFromString: NSData = data.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!
        // Instantiate a new default keychain query
        var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, key, dataFromString], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecValueDataValue])
        
        // Delete any existing items
        SecItemDelete(keychainQuery as CFDictionaryRef)

        if data == "" { return }
        
        // Add the new keychain item
        var status: OSStatus = SecItemAdd(keychainQuery as CFDictionaryRef, nil)
    }
    
    class func load(service: NSString, key: String) -> NSString? {
        // Instantiate a new default keychain query
        // Tell the query to return a result
        // Limit our results to one item
        var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, key, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])
        
        var dataTypeRef :Unmanaged<AnyObject>?
        
        // Search for the keychain items
        let status: OSStatus = SecItemCopyMatching(keychainQuery, &dataTypeRef)
        
        let opaque = dataTypeRef?.toOpaque()
        
        var contentsOfKeychain: NSString?
        
        if let op = opaque? {
            let retrievedData = Unmanaged<NSData>.fromOpaque(op).takeUnretainedValue()
            
            // Convert the data retrieved from the keychain into a string
            contentsOfKeychain = NSString(data: retrievedData, encoding: NSUTF8StringEncoding)
        } else {
            return nil
        }
        
        return contentsOfKeychain
    }
}

Now, __conversion() is also removed.

I updated the code for XCode 6.0 GM -- however I'm running into an issue where it only works when building for Debug not for Release, tracking that down

OK fair warning, the code above only works if the Swift Compiler - Code Generation level is set at "none", not at "Fastest" which is the default

Make sure to test the code against your release scheme

I can confirm the issue @alexbosworth mentioned exists in xcode 6.1 as well. Nice catch dude!

I have developed a Swift wrapper over the entire C Keychain API. See if it can be useful for you: https://github.com/deniskr/KeychainSwiftAPI

Another note about this, if you are using this code and you want the keys to be accessible from the lockscreen, like in a background fetch, you need to adjust the kSecAttrAccessible value

up! 👍