keychain保存App留存的信息

参考转载:iOS开发之如何在用户删除应用后保持一些数据: https://blog.csdn.net/u014410695/article/details/50623591

KeychainManager创建使用
.h

+(KeychainManager*)default;
/**根据字典存储对象到钥匙串*/
- (void)save:(NSString *)service data:(id)data;
/**根据字典读取钥匙串里的对象*/
- (id)load:(NSString *)service;
/**删除钥匙串里的数据*/
- (void)delete:(NSString *)service;

.m

+(KeychainManager*)default
{
    static KeychainManager *keychainManager = nil;
    if(keychainManager == nil)
    {
        keychainManager = [[KeychainManager alloc] init];
    }
    return keychainManager;
}
- (NSMutableDictionary *)getKeychainQuery:(NSString *)service {
    return [NSMutableDictionary dictionaryWithObjectsAndKeys:
            (id)kSecClassGenericPassword,(id)kSecClass,
            service, (id)kSecAttrService,
            service, (id)kSecAttrAccount,
            (id)kSecAttrAccessibleAfterFirstUnlock,(id)kSecAttrAccessible,
            nil];
}

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

- (id)load:(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:(id)kSecReturnData];
    [keychainQuery setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
    CFDataRef keyData = NULL;
    if (SecItemCopyMatching((CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) {
        @try {
//            ret = [NSKeyedUnarchiver unarchiveObjectWithData:(__bridge NSData *)keyData];
            ret = [NSKeyedUnarchiver unarchivedObjectOfClass:[NSObject class] fromData:(__bridge NSData *)keyData error:nil];
            
        } @catch (NSException *e) {
            NSLog(@"Unarchive of %@ failed: %@", service, e);
        } @finally {
        }
    }
    if (keyData)
        CFRelease(keyData);
    return ret;
}

- (void)delete:(NSString *)service {
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
    SecItemDelete((CFDictionaryRef)keychainQuery);
}