KeyChain

KeyChain 是苹果的密码管理系统，一个钥匙串可以包含多种类型的数据：密码 (-包括 网站，FTP服务器，SSH帐户，网络共享，无线网络，群组软件，加密磁盘映像 等-)，私钥，电子证书 和加密笔记等
主要讲的是开发用的东西，定义就不多赘述，有兴趣可以看上面wiki。

常用

关键代码

//存
[ToolUtils KeychainSave:PIN_KEYCHAIN data:newPwd];
//取
NSString *pin = [ToolUtils KeychainLoad:PIN_KEYCHAIN];
//删
[ToolUtils KeychainDelete:PIN_KEYCHAIN]

#pragma mark -
#pragma mark KeyChain methods
+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service {
    return [NSMutableDictionary dictionaryWithObjectsAndKeys:
            (__bridge id)kSecClassGenericPassword,(__bridge id)kSecClass,
            service, (__bridge id)kSecAttrService,
            service, (__bridge id)kSecAttrAccount,
            (__bridge id)kSecAttrAccessibleAfterFirstUnlock,(__bridge id)kSecAttrAccessible,
            nil];
}

+ (void)KeychainSave:(NSString *)service data:(id)data {
    //Get search dictionary
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
    //Delete old item before add new item
    SecItemDelete((__bridge CFDictionaryRef)keychainQuery);
    //Add new object to search dictionary(Attention:the data format)
    [keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(__bridge id)kSecValueData];
    //Add item to keychain with the search dictionary
    SecItemAdd((__bridge CFDictionaryRef)keychainQuery, NULL);
}

+ (id)KeychainLoad:(NSString *)service {
    id ret = nil;
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
    //Configure the search setting
    //Since in our simple case we are expecting only a single attribute to be returned (the password) we can set the attribute kSecReturnData to kCFBooleanTrue
    [keychainQuery setObject:(id)kCFBooleanTrue forKey:(__bridge id)kSecReturnData];
    [keychainQuery setObject:(__bridge id)kSecMatchLimitOne forKey:(__bridge id)kSecMatchLimit];
    CFDataRef keyData = NULL;
    if (SecItemCopyMatching((__bridge CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) {
        @try {
            ret = [NSKeyedUnarchiver unarchiveObjectWithData:(__bridge NSData *)keyData];
        } @catch (NSException *e) {
            NSLog(@"Unarchive of %@ failed: %@", service, e);
        } @finally {
        }
    }
    if (keyData)
        CFRelease(keyData);
    return ret;
}

+ (void)KeychainDelete:(NSString *)service {
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
    SecItemDelete((__bridge CFDictionaryRef)keychainQuery);
}