Application passwords in Swift using function overloading

Keychain.playground

import Security
import Foundation

// MARK: - Redefining boilerplate code

func SecKeychainOpen(path:String) -> SecKeychainRef? {
    
    var keychain:Unmanaged<SecKeychainRef>? = nil
    if SecKeychainOpen((path as NSString).UTF8String, &keychain) == errSecSuccess {
        return keychain?.takeRetainedValue()
    } else {
        return nil
    }
}

func SecKeychainCopySearchList() -> [SecKeychainRef]? {
    var keychains:Unmanaged<CFArray>? = nil
    if SecKeychainCopySearchList(&keychains) == errSecSuccess {
        if let keychains:AnyObject = keychains?.takeRetainedValue() {
            return map(keychains as [AnyObject], { $0 as SecKeychainRef })
        } else {
            return nil
        }
    } else {
        return nil
    }
}

func SecKeychainFindGenericPassword(keychains:[SecKeychainRef], serviceName:String, accountName:String) -> (String, SecKeychainItemRef)? {
    
    if let keychains = SecKeychainCopySearchList() {
        
        let serviceNameData = (serviceName as NSString).UTF8String
        let accountNameData = (accountName as NSString).UTF8String
        
        var passwordLength:UInt32 = 0
        var passwordData:UnsafeMutablePointer<Void> = nil
        var unmanagedItem:Unmanaged<SecKeychainItemRef>? = nil
        

        if SecKeychainFindGenericPassword(keychains, UInt32(strlen(serviceNameData)), serviceNameData, UInt32(strlen(accountNameData)), accountNameData, &passwordLength, &passwordData, &unmanagedItem) == errSecSuccess {
            
            let password = NSString(bytes: UnsafePointer(passwordData), length: Int(passwordLength), encoding: NSUTF8StringEncoding)!
            SecKeychainItemFreeContent(nil, passwordData)
            return (password, unmanagedItem!.takeRetainedValue())
            
        } else {
            return nil
        }
        
    } else {
        return nil
    }
}

func SecKeychainItemModifyData(item:SecKeychainItemRef, password:String) -> Bool {
    let passwordData = (password as NSString).UTF8String
    return SecKeychainItemModifyAttributesAndData(item, nil, UInt32(strlen(passwordData)), passwordData) == errSecSuccess
}

func SecKeychainAddGenericPassword(keychain:SecKeychainRef, serviceName:String, accountName:String, password:String) -> Bool {
    let serviceNameData = (serviceName as NSString).UTF8String
    let accountNameData = (accountName as NSString).UTF8String
    let passwordData = (password as NSString).UTF8String
    return SecKeychainAddGenericPassword(keychain, UInt32(strlen(serviceNameData)), serviceNameData, UInt32(strlen(accountNameData)), accountNameData, UInt32(strlen(passwordData)), passwordData, nil) == errSecSuccess
}

// MARK: - The fun begins here

if let keychain = SecKeychainOpen("login.keychain") {
    
    if let (_, item) = SecKeychainFindGenericPassword([keychain], "Setec Astronomy", "Password") {
        SecKeychainItemModifyData(item, "Modified")
    } else {
        SecKeychainAddGenericPassword(keychain, "Setec Astronomy", "Password", "Initial")
    }
}

if let (password, item) = SecKeychainFindGenericPassword(SecKeychainCopySearchList()!, "Setec Astronomy", "Password") {
    
    println("The secret word is is \(password)")
    
    if password == "Modified" {
        println("Too many secrets!")
        SecKeychainItemDelete(item)
    }
}