keychain的使用

通常情况下，我们用NSUserDefaults存储数据信息，但是对于一些私密信息，比如密码、证书等等，就需要使用更为安全的keychain了。keychain里保存的信息不会因App被删除而丢失，在用户重新安装App后依然有效，数据还在，所以也可以存储少量的数据。

首先导入Security.framework.

@interface MyKeychain : NSObject+ (void)save:(NSString *)service data:(id)data;+ (id)load:(NSString *)service;+ (void)delete:(NSString *)service;@end

@implementation MyKeychain+ (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)save:(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)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:(__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)delete:(NSString *)service {    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];    SecItemDelete((__bridge CFDictionaryRef)keychainQuery);}

然后把keychain访问对象封装一下：

@interface MyUserManeger : NSObject+(void)savePassWord:(NSString *)password;+(id)readPassWord;+(void)deletePassWord;@end

@implementation MyUserManegerstatic NSString * const KEY_IN_KEYCHAIN = @"com.userinfo";static NSString * const KEY_PASSWORD = @"com.password";+ (void)savePassWord:(NSString *)password{    NSMutableDictionary *usernamepasswordKVPairs = [NSMutableDictionary dictionary];    [usernamepasswordKVPairs setObject:password forKey:KEY_PASSWORD];    [MyKeychain save:KEY_IN_KEYCHAIN data:usernamepasswordKVPairs];}+ (id)readPassWord{    NSMutableDictionary *usernamepasswordKVPair = (NSMutableDictionary *)[MyKeychain load:KEY_IN_KEYCHAIN];    return [usernamepasswordKVPair objectForKey:KEY_PASSWORD];}+ (void)deletePassWord{    [MyKeychain delete:KEY_IN_KEYCHAIN];}@end

测试demo：http://download.csdn.net/detail/wanghuafeng123456/5808235

原文连接：http://blog.csdn.net/yiyaaixuexi/article/details/7688745