iOS，钥匙串(keychain) : Wrong passcode output

Question

好的。我在 View Controller 中设置用户密码:

KeychainItemWrapper *keychainWrapper =
[[KeychainItemWrapper alloc] initWithIdentifier:
 [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleIdentifier"] accessGroup:nil];

[keychainWrapper setObject:@"theUser" forKey:(__bridge id)(kSecAttrAccount)];
[keychainWrapper setObject:_passcode forKey:(__bridge id)(kSecValueData)];
NSLog(@"Saved pass: %@",_passcode);
NSLog(@"Returned pass: %@",[keychainWrapper objectForKey:(__bridge id)(kSecValueData)]);

NSlogs 返回我设置的相同字符串，假设它是 1234。稍后在 AppDelegate 中我尝试检索密码:

KeychainItemWrapper *keychainWrapper =
[[KeychainItemWrapper alloc] initWithIdentifier:
 [[[NSBundle mainBundle]infoDictionary] objectForKey:@"CFBundleIdentifier"] accessGroup:nil];
passcodeViewController.passcode = [keychainWrapper objectForKey:(__bridge id)(kSecValueData)];
NSLog(@"Pass: %@",[keychainWrapper setObject:_passcode forKey:(__bridge id)(kSecValueData)]);

然后邪恶就来了。 NSLog 返回:31323334。我做错了什么？

Answer 1

Keychain 将密码存储为 NSData，而不是 NSString。在存储密码之前，您需要对其进行编码。

NSData * passcodeData = [_passcode dataUsingEncoding:NSUTF8StringEncoding];
[keychainWrapper setObject:passcodeData forKey:(__bridge id)(kSecValueData)];

同样，检索到的对象是您需要解码的NSData。

NSData * passcodeData = [keychainWrapper objectForKey:(__bridge id)(kSecValueData)];
passcodeViewController.passcode = [[NSString alloc] initWithBytes:[passcodeData bytes]                                                             
                                                           length:[passcodeData length] 
                                                         encoding:NSUTF8StringEncoding];