钥匙串～存取删

有些数据需要记录在钥匙中：亲测可用

首先要导入 

#import

+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service {

    return [NSMutableDictionary dictionaryWithObjectsAndKeys:

            ( id)kSecClassGenericPassword,

            ( id)kSecClass,service,

            ( id)kSecAttrService,service,

            ( id)kSecAttrAccount,

            ( id)kSecAttrAccessibleAfterFirstUnlock,

            ( id)kSecAttrAccessible,

            nil];

}

+ (void)saveKeychainValue:(NSString *)sValue key:(NSString *)sKey {

    NSMutableDictionary * keychainQuery = [self getKeychainQuery:sKey];

    SecItemDelete(( CFDictionaryRef)keychainQuery);

    [keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:sValue] forKey:( id)kSecValueData];

    SecItemAdd(( CFDictionaryRef)keychainQuery, NULL);

}

+ (NSString *)readKeychainValue:(NSString *)sKey {

    NSString *ret = nil;

    NSMutableDictionary *keychainQuery = [self getKeychainQuery:sKey];

    [keychainQuery setObject:(id)kCFBooleanTrue forKey:( id)kSecReturnData];

    [keychainQuery setObject:( id)kSecMatchLimitOne forKey:( id)kSecMatchLimit];

    CFDataRef keyData = NULL;

    if (SecItemCopyMatching((__bridge CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) {

        @try {

            ret = (NSString *)[NSKeyedUnarchiver unarchiveObjectWithData:(__bridge NSData *)keyData];

        } @catch (NSException *e) {

            NSLog(@"Unarchive of %@ failed: %@", sKey, e);

        } @finally {

        }

    }

    if (keyData)

        CFRelease(keyData);

    return ret;

}

+ (void)deleteKeychainValue:(NSString *)sKey {

    NSMutableDictionary *keychainQuery = [self getKeychainQuery:sKey];

    SecItemDelete((__bridge CFDictionaryRef)keychainQuery);

}