ios - 触控 ID : How to get touch id authentication attempts?

Question

我需要实现触摸 ID，并且必须向用户显示剩余身份验证尝试的警报。下面的代码我正在使用。

在一次错误的身份验证尝试后不会调用回复 block 。它在 3 之后被调用继续错误的身份验证尝试。有没有什么方法可以统计错误的身份验证尝试……？

LAContext *myContext = [[LAContext alloc] init];

NSError *authError = nil;
NSString *myLocalizedReasonString = @"Touch ID Test to show Touch ID working in a custom app";

if ([myContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&authError]) {
    [myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
              localizedReason:myLocalizedReasonString
                        reply:^(BOOL success, NSError *error) {
                            if (success) {
                                dispatch_async(dispatch_get_main_queue(), ^{
                                    [self performSegueWithIdentifier:@"Success" sender:nil];
                                });
                            } else {
                                dispatch_async(dispatch_get_main_queue(), ^{
                                    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error"
                                                                                        message:error.description
                                                                                       delegate:self
                                                                              cancelButtonTitle:@"OK"
                                                                              otherButtonTitles:nil, nil];
                                    [alertView show];
                                    NSLog(@"Switch to fall back authentication - ie, display a keypad or password entry box");
                                });
                            }
                        }];
} else {
    dispatch_async(dispatch_get_main_queue(), ^{
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error"
                                                            message:authError.description
                                                           delegate:self
                                                  cancelButtonTitle:@"OK"
                                                  otherButtonTitles:nil, nil];
        [alertView show];
    });
}

Answer 1

我仔细阅读了文档，不可能在每次失败的尝试中都显示警报。只需引用文档 LocalAuthentication in iOS .

您可以在不同的错误情况下显示警报。第 3 次尝试失败后 LAError.authenticationFailed 将被调用，第 5 次尝试失败后 LAError.touchIDLockout 将被调用。您可以在此处显示警报。有关更多信息，请参阅 Apple LAError documentation.