将唯一标示符保存在钥匙串中ps：udid是参数，需要传

本文链接：https://blog.youkuaiyun.com/qq_16904879/article/details/51123016

本文详细介绍了如何使用Objective-C在iOS系统中通过Keychain存储和更新用户唯一标识符（UDID），包括初始化字典、设置Keychain属性、获取或更新UDID的过程，并通过错误处理确保操作成功。

NSMutableDictionary *dictForAdd = [[NSMutableDictionary alloc] init];
    
    [dictForAdd setValue:(id)kSecClassGenericPassword forKey:(id)kSecClass];
    [dictForAdd setValue:[NSString stringWithUTF8String:kKeychainUDIDItemIdentifier] forKey:kSecAttrDescription];
    
    [dictForAdd setValue:@"UUID" forKey:(id)kSecAttrGeneric];
    
    // Default attributes for keychain item.
    [dictForAdd setObject:@"" forKey:(id)kSecAttrAccount];
    [dictForAdd setObject:@"" forKey:(id)kSecAttrLabel];
    
    
    
    
    const char *udidStr = [udid UTF8String];
    NSData *keyChainItemValue = [NSData dataWithBytes:udidStr length:strlen(udidStr)];
    [dictForAdd setValue:keyChainItemValue forKey:(id)kSecValueData];
    
    OSStatus writeErr = noErr;
    if ([StaticTools getUDIDFromKeyChain]) {        // there is item in keychain
        [StaticTools updateUDIDInKeyChain:udid];
        [dictForAdd release];
        return YES;
    }
    else {          // add item to keychain
        writeErr = SecItemAdd((CFDictionaryRef)dictForAdd, NULL);
        if (writeErr != errSecSuccess) {
            NSLog(@"Add KeyChain Item Error!!! Error Code:%d", (int)writeErr);
            
            [dictForAdd release];
            return NO;
        }
        else {
            NSLog(@"Add KeyChain Item Success!!!");
            [dictForAdd release];
            return YES;
        }
    }
    
    [dictForAdd release];
    return NO;