credential.swift

import Foundation
public class CredentialHelper {
    
    // MARK: Init
    private var host: String
    private var protectionSpace: NSURLProtectionSpace
    
    public init(host: String) {
        self.host = host
        protectionSpace = NSURLProtectionSpace(host: host, port: 0, `protocol`: "http", realm: nil, authenticationMethod: nil)
    }
    
    // MARK: Store credentials
    private func storeCredential(key: String, value: String) {
        let credential = NSURLCredential(user:key, password: value, persistence: .Permanent)
        NSURLCredentialStorage.sharedCredentialStorage().setCredential(credential, forProtectionSpace: protectionSpace)
    }
    
    private func storeDefaultCredential(key: String, value: String) {
        let credential = NSURLCredential(user:key, password: value, persistence: .Permanent)
        NSURLCredentialStorage.sharedCredentialStorage().setDefaultCredential(credential, forProtectionSpace: protectionSpace)
    }
    
    // MARK: Retrieve credentials
    private var credentials: [NSObject:AnyObject] {
        if let dict = NSURLCredentialStorage.sharedCredentialStorage().credentialsForProtectionSpace(protectionSpace) {
            return dict
        }
        return [NSObject:AnyObject]()
    }
    
    public var credentialCount: Int {
        return credentials.count
    }
    
    private func credentialForKey(key: String) -> NSURLCredential? {
        if let credential: NSURLCredential = credentials[key] as? NSURLCredential {
            return credential
        }
        return nil
    }
    
    private func valueForKey(key: String) -> String? {
        if let credential = credentialForKey(key) {
            return credential.password
        }
        return nil
    }
    
    // MARK: Edit credentials
    public func removeCredential(key: String) {
        if let credential: NSURLCredential = credentials[key] as? NSURLCredential {
            NSURLCredentialStorage.sharedCredentialStorage().removeCredential(credential, forProtectionSpace: protectionSpace)
        }
    }
    
    public func removeAllCredentials() {
        for key in credentials.keys {
            if let key = key as? String {
                removeCredential(key)
            }
        }
    }
    
    // MARK: Default credentials
    private var defaultCredential: NSURLCredential? {
        return NSURLCredentialStorage.sharedCredentialStorage().defaultCredentialForProtectionSpace(protectionSpace)
    }
    
    private func setDefaultCredential(key: String) {
        if let value = self[key] {
            let credential = NSURLCredential(user:key, password: value, persistence: .Permanent)
            NSURLCredentialStorage.sharedCredentialStorage().setDefaultCredential(credential, forProtectionSpace: protectionSpace)
        } else {
            print("Credential not found. Default credential is unchanged")
        }
    }
    
    public var defaultKey: NSString? {
        get {return defaultCredential?.user}
        set (newValue) {
            if let newValue = newValue {
                setDefaultCredential(newValue as String)
            } else {
                print("Nil key. Default credential is unchanged")
            }
        }
    }
    
    // I strongly considered letting assignment to nil remove the entire credential here
    public var defaultValue: NSString? {
        get {return defaultCredential?.password}
        set (newValue) {
            if let newValue = newValue {
                if let defaultKey = defaultKey {
                    storeCredential(defaultKey as String, value: newValue as String)
                }
            } else {
                print("Nil value. Default credential is unchanged")
            }
        }
    }
    
    // MARK: Dictionary access -- preferred entry point for assignment and retrieval
    public subscript (key: String) -> String? {
        get {return valueForKey(key)}
        set(newValue) {
            if let newValue = newValue {
                storeCredential(key, value: newValue)
            } else {
                removeCredential(key)
            }
        }
    }
}