How do I force the user to select a date on iOS?

Question

When creating a new entity in an iPad application one of the mandatory properties is a deliver date. There is no way to predict this deliver date. Choosing the wrong deliver date leads to all kinds of problem. My idea is that by forcing the user to select a date, rather than providing a default one, some thought will go into selecting the date and thus minimize faulty dates.

Normally when a new entity the user has some kind of paper as a base. Later on changes are made to the entity but the paper used when creating the entity is not necessarily available. Which means that the deliver date should be selected when creating the entity. It is possible to change the deliver date after the entity is created.

The problem with the standard date picker control on iOS is that it is not possible to start in an unselected state. How can I force the user to make an active choice when selecting the deliver date? After the entity is created the normal date picker would work fine but I would prefer to use the same method for selecting the date in both cases.

There is an interval of valid dates but the interval is quite big which means it is not really practical to start an invalid date and force the user to scroll to a valid date.

Answer 1

My idea is that by forcing the user to select a date, rather than providing a default one, some thought will go into selecting the date and thus minimize faulty dates.

I think you overestimate people's thought processes. If they have to choose a date they'll pick the first available one that's allowed and will get frustrated if it's not obvious what date(s) they can select.

My bank offers an online bill payment service and you select the date you want the payment to go out. It presents a date picker with the available dates highlighted, but still gets it wrong sometimes so you can select a date that it actually invalid. This leads to an annoying "your payment can't be processed on that date" message and having to repeat part of the process.

... one of the mandatory properties is a deliver date. There is no way to predict this deliver date. Choosing the wrong deliver date leads to all kinds of problem.

If it's mandatory but unpredictable and choosing the wrong one is "a bad thing" then perhaps you need to rethink your workflow. Without knowing more about the application I can't suggest an alternative.

Answer 2

What a lot of date entry forms do is have a blank field with a button to bring up the date picker. Blank is an illegal value, so not selecting a date doesn't let you go forward unless you've pressed the button and picked something. You could also try making the picker default to yesterday, and make yesterday an illegal value, thus catching the case where someone just clicks on the picker and shuts it down again.

Answer 3

I like DJClayworth's answer...one other idea is to put the date selection on its own screen. This gives you an opportunity to really emphasize the importance of selecting the correct date. It will be the only thing users are focusing on for that whole screen, so they'll be more likely to pay attention. That said, there are no guarantees.