Help: How to skip installing previously downloaded update (version A) and directly update to latest version (version B) when checking for updates?

[Tom-and-Jerry-gif]

Sparkle version:2.8.0

Suppose version A has already been downloaded locally but not installed, and version B has just been released on the server. When triggering checkForUpdate, the application immediately restarts and, after restarting, automatically downloads version B in the background. After checking the source code, I found that in the checkForUpdatesWithDriver method, if the installer process has already been started, the installation is triggered directly.

if (installerInProgress) {
        // Resume an update that has already begun installing in the background
        [_driver resumeInstallingUpdate];
    } else if (_resumableUpdate != nil) {
        // Resume an update or info that has already been downloaded
        [_driver resumeUpdate:(id<SPUResumableUpdate> _Nonnull)_resumableUpdate];
    } else {
        // Check that the parameterized feed URL is valid
        NSURL *theFeedURL = [self parameterizedFeedURL];
        if (theFeedURL == nil) {
            // I think this is really unlikely to occur but better be safe
            // We will not schedule a next update check if the feed URL cannot be formed
            SULog(SULogLevelError, @"Error: failed to retrieve feed URL for bundle");
            
            abortUpdateDriver([NSError errorWithDomain:SUSparkleErrorDomain code:SUInvalidFeedURLError userInfo:@{ NSLocalizedDescriptionKey: @"Sparkle cannot form a valid feed URL." }], NO);
        } else {
            // Check for new updates
            [_driver checkForUpdatesAtAppcastURL:theFeedURL withUserAgent:_userAgentString httpHeaders:_httpHeaders];
        }
    }

Is there a way to skip installing version A and fetch the update configuration for version B directly when checking for updates, without restarting the application in this situation? Alternatively, is it possible to provide a cancellation method to remove the previously downloaded installation package for version A and clear its update records (and perhaps exit the installer process too)?

[zorgiepoo]

When triggering checkForUpdate, the application immediately restarts..

It’s not immediately or controlled by the developer in this case upon checking for updates (unless the user driver is being abused). Assuming the update has been automatically downloaded/started installing in the background, the user is provided the option to relaunch the app from an update that has already started installing in the background. Or if they quit the app the update can install automatically.

The user is also provided another option to skip the update which will cancel it. Again not controlled by the developer.

and, after restarting, automatically downloads version B in the background

This shouldn't be immediate btw unless you are force triggering a background update check.

[Tom-and-Jerry-gif]

Thank you for your reply !

Correction: The restart is actually triggered when checkForUpdateInBackground is called in the code.

So, in the scenario where an update installer has already been downloaded locally (but not installed), does it mean that we should avoid calling checkForUpdateInBackground again?

Due to our business requirements, we want the silent update check to occur only under certain conditions, so we did not use Sparkle’s built-in scheduled silent update feature—instead, we use a timer to trigger checkForUpdateInBackground periodically for silent update checks.

In this silent update scenario, does Sparkle require that version A must be installed successfully before the application can fetch and apply version B?

[zorgiepoo]

Correction: The restart is actually triggered when checkForUpdateInBackground is called in the code.

Assuming automatic updates are enabled: if an update has not been downloaded, it will try to download/stage the update for installation in the background silently. Sparkle may choose to immediately prompt the user to install the update if user authorization / interaction is required to start installing the update (or other conditions are met like the update is marked critical). Otherwise, the next time checkForUpdateInBackground is called, it will present the already-downloaded update to the user to make a decision (install and relaunch or skip). Sparkle's default scheduler in this case calls checkForUpdateInBackground again at an "impatient" scheduled interval if the user has not quit their app by then, which is set to 1 week, but it's planned to be configurable in the next Sparkle release.

The app restarting is not triggered by Sparkle itself, it's triggered through by the user. Or the developer if they return YES in -updater:willInstallUpdateOnQuit:immediateInstallationBlock: which is another path if updates can be installed silently in the background (and stops Sparkle's next update cycles from running).

Sparkle tries to install a staged update whenever the user quits their app, or when the user decides to install it after being notified a week later, or when the user decides to install it upon checking for updates themselves, or upon the developer triggering the install/relaunch in the delegate method above.

In this silent update scenario, does Sparkle require that version A must be installed successfully before the application can fetch and apply version B?

Yes it is currently like this, unless the user skips the update.

The simplest usage of checkForUpdateInBackground is not calling it manually and relying on Sparkle's scheduler. The next simplest usage is only calling it right after starting the updater (near app launch), and checking that the user hasn't disabled automatic update checks (automaticallyChecksForUpdates, or other means if you're disabling sparkle's scheduler).

There have been requests for Sparkle to automatically cancel the current update and download the newer one.. Who knows maybe the behavior will change far out.

[Tom-and-Jerry-gif]

Got it, thanks for your reply!