+ (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] 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];
} @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);
}
上面的加号方法，写在一个新类中，（SPDBKeyChain）
调方法：
1.存：
NSMutableDictionary *key_chain = [NSMutableDictionary dictionary];
[key_chain setObject:forKey:];
[SPDBKeyChain save:@"FingerPrintData" data:key_chain];
2.取:
NSMutableDictionary *key_chain = (NSMutableDictionary *)[SPDBKeyChain load:@"FingerPrintData"];
NSString *string = [usernamepasswordKVPairs objectForKey:@"FingerPrintData"];
NSLog(@"string---%@",string);
3.删：
[SPDBKeyChain delete:@"FingerPrintData"];
keychain备份
iOS的Keychain由系统管理并且进行加密，Keychain内的信息会随着iPhone的数据一起备份。但是kSecAttrAccessible 属性被设置为后缀是ThisDeviceOnly的数据会被以硬件相关的密钥(key)加密。并且不会随着备份移动至其他设备。
Keychain从iOS7.0开始也支持iCloud备份。把kSecAttrSynchronizable属性设置为@YES，这样后Keychain就能被iCloud备份并且跨设备分享。
不过在添加kSecAttrSynchronizable属性后，这条属性会被作为每条Keychain Item的主要的Key之一，所以在搜索，更新，删除的时候如果查询字典内没有这一条属性，item就匹配不到。
