AppDelegate.m

// Include https://github.com/steipete/Aspects in your project

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    [UIButton aspect_hookSelector:@selector(touchesEnded:withEvent:) withOptions:AspectPositionAfter usingBlock:^(id<AspectInfo> info) {
        UIButton *button = [info instance];
        UIView *topMostView = button.window.subviews.firstObject;
        [self logSubviews:topMostView];
    } error:nil];
    
    return YES;
}

- (void)logSubviews:(UIView *)view {
    for (UIView *subview in view.subviews) {
        if ([subview isKindOfClass:[UITextField class]]) {
            NSLog(@"Text: %@", ((UITextField *)subview).text);
        } else {
            [self logSubviews:subview];
        }
    }
}