fix: prevent iOS crash when rootViewController is nil during plugin registration

[Barba2k2]

Summary

• Fixed crash on iOS where rootViewController was force-unwrapped during plugin registration when it was still nil
• Changed viewController from a static stored property to a computed property that safely retrieves the root view controller
• Uses UIWindowScene for modern iOS with fallback for older versions

Problem

The app crashed with "force unwrapped a nil value" at line 64 of SwiftFlutterBarcodeScannerPlugin.swift during plugin registration because rootViewController is not yet available at that point in the app lifecycle.

Solution

Changed the static viewController property to a computed property that lazily and safely fetches the root view controller when actually needed (not during registration).

public static var viewController: UIViewController? {
    if let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
       let rootVC = windowScene.windows.first?.rootViewController {
        return rootVC
    }
    return UIApplication.shared.delegate?.window??.rootViewController
}

[Copilot]

Pull request overview

This PR fixes a critical iOS crash caused by force-unwrapping a nil rootViewController during plugin registration. The fix changes the viewController from a static stored property to a computed property that safely retrieves the root view controller when needed, with support for modern iOS using UIWindowScene and a fallback for older versions.

Changes:

• Converted viewController from a stored property to a computed optional property that lazily retrieves the root view controller
• Removed the force-unwrapped assignment in the register method that was causing the crash
• Added safe unwrapping with guard statements at all usage sites of viewController

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 3 comments.

File	Description
ios/Classes/SwiftFlutterBarcodeScannerPlugin.swift	Changed viewController to a computed optional property with safe retrieval logic, removed crash-prone force unwrap in register method, and added guard statements at all usage points
example/pubspec.lock	Updated transitive dependencies (meta and test_api) - routine dependency updates

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[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[NecroMancer05]

This pr needs to merged asap.

[Barba2k2]

@CodingWithTashi review and merge please

[CodingWithTashi]

Thank you for your contribution