//To identify a search engine, newsletter name, or other source.
// (for example 'AdWords', 'Bing', 'E-Mail Newsletter')
ReferralProperty * RFSource;
//To identify a medium such as email or cost-per-install.
ReferralProperty * RFMedium;
//To identify a specific product promotion or strategic campaign.
//(for example 'Snow Boots')
ReferralProperty * RFCampaign;
//To differentiate ads or links that point to the same URL.
//(for example some ads might advertise 'Warm Snow Boots' and others might advertise 'Durable Snow Boots')
ReferralProperty * RFContent;
//To note the keywords for this ad.
// for example 'shoes+boots')
ReferralProperty * RFTerm;
[ReferralProperty Custom:@"your_key_name"];