[ios] Delete keychain items when an app is uninstalled

I am using idandersen's scifihifi-iphone code for keychain and save password using

[SFHFKeychainUtils storeUsername:@"User" andPassword:@"123"
              forServiceName:@"TestService" updateExisting:YES error:&error];

When I delete the application from the device, the password remains in the keychain.

I want to remove the password from the keychain when the user deletes the application from the device. How can I do this?

For users looking for a Swift 3.0 version of @amro's answer:

let userDefaults = UserDefaults.standard

if !userDefaults.bool(forKey: "hasRunBefore") {
     // Remove Keychain items here

     // Update the flag indicator
     userDefaults.set(true, forKey: "hasRunBefore")
}

*note that synchronize() function is deprecated

For those looking for a Swift version of @amro's answer:

    let userDefaults = NSUserDefaults.standardUserDefaults()

    if userDefaults.boolForKey("hasRunBefore") == false {

        // remove keychain items here


        // update the flag indicator
        userDefaults.setBool(true, forKey: "hasRunBefore")
        userDefaults.synchronize() // forces the app to update the NSUserDefaults

        return
    }

Files will be deleted from your app's document directory when the user uninstalls the app. Knowing this, all you have to do is check whether a file exists as the first thing that happens in application:didFinishLaunchingWithOptions:. Afterwards, unconditionally create the file (even if it's just a dummy file).

If the file did not exist at time of check, you know this is the first run since the latest install. If you need to know later in the app, save the boolean result to your app delegate member.

There is no trigger to perform code when the app is deleted from the device. Access to the keychain is dependant on the provisioning profile that is used to sign the application. Therefore no other applications would be able to access this information in the keychain.

It does not help with you aim to remove the password in the keychain when the user deletes application from the device but it should give you some comfort that the password is not accessible (only from a re-install of the original application).

Just add an app setting bundle and implement a toggle to reset the keychain on app restart or something based on the value selected through settings (available through userDefaults)

This seems to be the default behavior on iOS 10.3 based on behavior people have been witnessing in beta #2. Haven't found any official documentation about this yet so please comment if you have.

C# Xamarin version

    const string FIRST_RUN = "hasRunBefore";
    var userDefaults = NSUserDefaults.StandardUserDefaults;
    if (!userDefaults.BoolForKey(FIRST_RUN))
    {
        //TODO: remove keychain items
        userDefaults.SetBool(true, FIRST_RUN);
        userDefaults.Synchronize();
    }

... and to clear records from the keychain (TODO comment above)

        var securityRecords = new[] { SecKind.GenericPassword,
                                    SecKind.Certificate,
                                    SecKind.Identity,
                                    SecKind.InternetPassword,
                                    SecKind.Key
                                };
        foreach (var recordKind in securityRecords)
        {
            SecRecord query = new SecRecord(recordKind);
            SecKeyChain.Remove(query);
        }

@amro's answer translated to Swift 4.0:

if UserDefaults.standard.object(forKey: "FirstInstall") == nil {
    UserDefaults.standard.set(false, forKey: "FirstInstall")
    UserDefaults.standard.synchronize()
}