Allow to use custom UIViewController name when tracking breadcumbs

[m1entus]

Problem Statement

I would love to be able to report custom controller name when sending breadcumbs. Unfortunately we are using modules and each of our feature module UIViewControleller is ViewController as a class Feature.ViewController and seems it is always showing ViewController as a name in the panel. Ideally instead of NSString *name = [SwiftDescriptor getObjectClassName:controller]; we could use some like if ([controller conformsToProtocol:@protocol(ViewControllerBreadcrumbTracking)] then use custom name instead of getObjectClassName.

protocol ViewControllerBreadcrumbTracking {
    var screenName: String { get }
}

#if SENTRY_HAS_UIKIT
- (void)swizzleViewDidAppear
{

    // SentrySwizzleInstanceMethod declaration shadows a local variable. The swizzling is working
    // fine and we accept this warning.
#    pragma clang diagnostic push
#    pragma clang diagnostic ignored "-Wshadow"

    static const void *swizzleViewDidAppearKey = &swizzleViewDidAppearKey;
    SEL selector = NSSelectorFromString(@"viewDidAppear:");
    SentryBreadcrumbTracker *__weak weakSelf = self;

    SentrySwizzleMode mode = SentrySwizzleModeOncePerClassAndSuperclasses;

#    if defined(TEST) || defined(TESTCI)
    // some tests need to swizzle multiple times, once for each test case. but since they're in the
    // same process, if they set something other than "always", subsequent swizzles fail. override
    // it here for tests
    mode = SentrySwizzleModeAlways;
#    endif // defined(TEST) || defined(TESTCI)

    SentrySwizzleInstanceMethod(UIViewController.class, selector, SentrySWReturnType(void),
        SentrySWArguments(BOOL animated), SentrySWReplacement({
            SentryBreadcrumb *crumb = [[SentryBreadcrumb alloc] initWithLevel:kSentryLevelInfo
                                                                     category:@"ui.lifecycle"];
            crumb.type = @"navigation";
            crumb.data = [SentryBreadcrumbTracker fetchInfoAboutViewController:self];

            [weakSelf.delegate addBreadcrumb:crumb];

            SentrySWCallOriginal(animated);
        }),
        mode, swizzleViewDidAppearKey);
#    pragma clang diagnostic pop
}

+ (NSDictionary *)fetchInfoAboutViewController:(UIViewController *)controller
{
    NSMutableDictionary *info = @{}.mutableCopy;

    info[@"screen"] = [SwiftDescriptor getObjectClassName:controller];

    if ([controller.navigationItem.title length] != 0) {
        info[@"title"] = controller.navigationItem.title;
    } else if ([controller.title length] != 0) {
        info[@"title"] = controller.title;
    }

    info[@"beingPresented"] = controller.beingPresented ? @"true" : @"false";

    if (controller.presentingViewController != nil) {
        info[@"presentingViewController"] =
            [SwiftDescriptor getObjectClassName:controller.presentingViewController];
    }

    if (controller.parentViewController != nil) {
        info[@"parentViewController"] =
            [SwiftDescriptor getObjectClassName:controller.parentViewController];
    }

    if (controller.view.window != nil) {
        info[@"window"] = controller.view.window.description;
        info[@"window_isKeyWindow"] = controller.view.window.isKeyWindow ? @"true" : @"false";
        info[@"window_windowLevel"] =
            [NSString stringWithFormat:@"%f", controller.view.window.windowLevel];
        info[@"is_window_rootViewController"]
            = controller.view.window.rootViewController == controller ? @"true" : @"false";
    }

    return info;
}

Solution Brainstorm

Use

protocol ViewControllerBreadcrumbTracking {
    var screenName: String { get }
}

If viewController responds to ViewControllerBreadcrumbTracking then use screenName instead of [SwiftDescriptor getObjectClassName:controller]

Are you willing to submit a PR?

I could if we agree on solution.

[philipphofmann]

@m1entus, your issue talks about breadcumbs but the code snipped refers to transactions. I guess that's a mistake?

For breadcrumbs, you could maybe use beforeBreadcrumb to set the proper UIViewController name: https://docs.sentry.io/platforms/apple/configuration/options/#before-breadcrumb. Does that work for you? If not, please elaborate.

[m1entus]

@philipphofmann Sorry wrong code, but it is using the same methods which is [SwiftDescriptor getObjectClassName:controller] (i updated PR). Not sure how beforeBreadcrumb will help in that case if breadcumb data already will have String which is ViewController, i attached screenshot to show you a preview how it look like for us:

Ideally for me to have: screen: MyFeature.ViewController.

FIY: marking MyFeature.ViewController as annotation for Objective-C @objc(MyFeatureViewController) doesn't help.

[brustolin]

protocol ViewControllerBreadcrumbTracking {
var screenName: String { get }
}

I like this idea.
If you're willing to open a PR, I don’t see why not following this approach.