Hook for the triggerCampaign pipeline to always associate a campaign to a visit.

AssociateCampaignToVisit.cs

public class AssociateCampaignToVisit : TriggerCampaignProcessor
{
    public override void Process(TriggerCampaignArgs args)
    {
        Assert.ArgumentNotNull((object)args, "args");

        // Always associate the campaign to the current visit when triggered
        Sitecore.Analytics.Tracker.CurrentVisit.CampaignId = args.Definition.ID.ToGuid();
    }
}