import UIKit
import Security

class Keychain {

    class func save(key: String, data: NSData) -> Bool {
        let query = [
            kSecClass as String       : kSecClassGenericPassword as String,
            kSecAttrAccount as String : key,
            kSecValueData as String   : data ]

        SecItemDelete(query as CFDictionaryRef)

        let status: OSStatus = SecItemAdd(query as CFDictionaryRef, nil)

        return status == noErr
    }

    class func load(key: String) -> NSData? {
        let query = [
            kSecClass as String       : kSecClassGenericPassword,
            kSecAttrAccount as String : key,
            kSecReturnData as String  : kCFBooleanTrue,
            kSecMatchLimit as String  : kSecMatchLimitOne ]

        var dataTypeRef :Unmanaged<AnyObject>?

        let status: OSStatus = SecItemCopyMatching(query, &dataTypeRef)

        if status == noErr {
            return (dataTypeRef!.takeRetainedValue() as NSData)
        } else {
            return nil
        }
    }

    class func delete(key: String) -> Bool {
        let query = [
            kSecClass as String       : kSecClassGenericPassword,
            kSecAttrAccount as String : key ]

        let status: OSStatus = SecItemDelete(query as CFDictionaryRef)

        return status == noErr
    }


    class func clear() -> Bool {
        let query = [ kSecClass as String : kSecClassGenericPassword ]

        let status: OSStatus = SecItemDelete(query as CFDictionaryRef)

        return status == noErr
    }

}