iOS 中钥匙串的使用

import Foundation

let KEY_IN_KEYCHAIN = "com.xxx......"
let KEY_PASSWORD = "com.xxx......"

class Keychain {
    
    internal class func saveUuid(_ uuid: String) {
        let saveDict = NSMutableDictionary()
        saveDict.setObject(uuid, forKey: KEY_PASSWORD as NSCopying)
        save(KEY_IN_KEYCHAIN, data: saveDict)
    }
    
    internal class func readUuid() -> AnyObject? {
        let savedDict = load(KEY_IN_KEYCHAIN) as? NSDictionary
        var result : AnyObject?
        result = savedDict?.object(forKey: KEY_PASSWORD) as AnyObject?
        return result
    }
        
    fileprivate class func getKeychainQuery(_ service: String) -> NSMutableDictionary {
        let keychainDict : NSMutableDictionary = [kSecClass as String:kSecClassGenericPassword as String,
                                                  kSecAttrAccount as String:service,
                                                  kSecAttrService as String:service,
                                                  kSecAttrAccessible as String:kSecAttrAccessibleAfterFirstUnlock as String]
        return keychainDict
    }
    
    fileprivate class func save(_ service: String, data:AnyObject) {
        let keychainQuery = getKeychainQuery(service)
        SecItemDelete(keychainQuery as CFDictionary)
        keychainQuery.setObject(NSKeyedArchiver.archivedData(withRootObject: data), forKey: kSecValueData as String as String as NSCopying)
        SecItemAdd(keychainQuery as CFDictionary, nil)
    }
    
    fileprivate class func load(_ service: String) -> AnyObject? {
        let keychainQuery = getKeychainQuery(service)
        keychainQuery.setObject(kCFBooleanTrue, forKey: kSecReturnData as! NSCopying)
        keychainQuery.setObject(kSecMatchLimitOne, forKey: kSecMatchLimit as! NSCopying)
        
        var keyData : AnyObject?
        var result : AnyObject?
        
        if SecItemCopyMatching(keychainQuery as CFDictionary, &keyData) == noErr{
            result = NSKeyedUnarchiver.unarchiveObject(with: keyData as! Data) as AnyObject?
        }
        
        return result
    }
    
    fileprivate class func delete(_ service: String) {
        let keychainQuery = getKeychainQuery(service)
        SecItemDelete(keychainQuery as CFDictionary)
    }
}