Attacks do not come from nowhere: something usually precedes them. Logging what you eat is what lets you find your own trigger instead of avoiding a whole list just in case.
Log meals and pain episodes, and the app shows what keeps appearing beforehand, with how many coincidences. Many people find out theirs is beer and not shellfish, or the other way round.
Not everything high in purines weighs the same, and fructose and alcohol count more than people expect. Every warning comes with its explanation and its source, so you know which one actually matters to you.
Log every reading and see it on a line with its range. It is the number that says whether treatment is working, and a trend says more than one day's value.