Load Login from Keychain Swift

loadLogin.swift

func load(service: NSString, userName:String) -> NSString?
{
    //Create the query keychain
    let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, userName, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])
        
    var dataTypeRef : Unmanaged<AnyObject>?
        
    // Search for the keychain items
    let status: OSStatus = withUnsafeMutablePointer(&dataTypeRef) { SecItemCopyMatching(keychainQuery as CFDictionaryRef, UnsafeMutablePointer($0)) }
  
    print(status)
    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)
    }
                
    return contentsOfKeychain
}