Rule Definition
Before using evaluatePolicy: method, make sure you have checked the LAContext using canEvaluatePolicy method just before.
Remediation
Make sure you have implemented the canEvaluatePolicy method just before using the evaluatePolicy method
Violation Code Sample
LAContext *myContext = [[LAContext alloc] init];
NSError *authError = nil;
NSString *myLocalizedReasonString = <#String explaining why app needs authentication#>;
[myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
localizedReason:myLocalizedReasonString
reply:^(BOOL success, NSError *error) {
if (success) {
// User authenticated successfully, take appropriate action
} else {
// User did not authenticate successfully, look at error and take appropriate action
}
}];
}
Fixed Code Sample
LAContext *myContext = [[LAContext alloc] init];
NSError *authError = nil;
NSString *myLocalizedReasonString = <#String explaining why app needs authentication#>;
if ([myContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&authError]) {
[myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
localizedReason:myLocalizedReasonString
reply:^(BOOL success, NSError *error) {
if (success) {
// User authenticated successfully, take appropriate action
} else {
// User did not authenticate successfully, look at error and take appropriate action
}
}];
} else {
// Could not evaluate policy; look at authError and present an appropriate message to user
}
Reference
https://developer.apple.com/library/ios/documentation/LocalAuthentication/Reference/LocalAuthentication_Framework/
Related Technologies
Technical Criterion
Programming Practices - Unexpected Behavior
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