使用KeychainItemWrapper的问题

Question

我使用以下代码从iPhone钥匙串中检索登录凭据:

KeychainItemWrapper *wrapper = [[KeychainItemWrapper alloc] initWithIdentifier:@"Test" accessGroup:nil];
NSString *username = [wrapper objectForKey:(id)kSecAttrAccount];
NSString *password = [wrapper objectForKey:(id)kSecValueData];
[wrapper release];

我的第一次用户启动应用程序,无论用户名密码也可以从钥匙串中检索的印象,所以username和password应该等于nil.但是,我无法使用打印出任何这些变量NSLog.

有什么建议？

Answer 1

KeychainItemWrapper *wrapper = [[KeychainItemWrapper alloc] initWithIdentifier:@"Test" accessGroup:nil];
NSString *username = [wrapper objectForKey:(id)kSecAttrAccount];
NSString *password = [wrapper objectForKey:(id)kSecValueData];

// initially all these are empty
NSLog(@"username - %@", username); // username - 
NSLog(@"password - %@", password); // password - 

//if empty set your credentials
if ( [username isEqualToString:@""] ) {
    [wrapper setObject:@"your username here" forKey:(id)kSecAttrAccount];
}
if ( [password isEqualToString:@""] ) {
    [wrapper setObject:@"your password here" forKey:(id)kSecValueData];
}

//get the latest credentials - now you have the set values
username = [wrapper objectForKey:(id)kSecAttrAccount];
password = [wrapper objectForKey:(id)kSecValueData];

NSLog(@"username - %@", username); // username - your username here
NSLog(@"password - %@", password); // password - your password here

// reset your keychain items - if  needed
[wrapper resetKeychainItem];
[wrapper release];

Answer 2

您的假设是错误的 - 在创建时,"kSecAttrAccount"和"kSecValueData"未设置为nil.它们被设置为空字符串(即"").所以,这段代码将返回true:

[username isEqualToString:@""]    // returns true on creation