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iOS

Posted by Ben Barry
Ben Barry
491 Points

Check to see if NSDate is empty

Using Swift I want to check to see if a date is present before doing formatting to it, but the following code does not work. Any Ideas?

if(date != nil){ //do your formatting here }

Ben Barry
Ben Barry
491 Points

Thanks for the quick reply. I think it can only be a NSDate or nil, but since I am very new to core data and iOS programming I may be wrong.

The idea is that if someone has not entered the date to give them an opportunity to do so.

This is not my area either. So I appreciate your help.

Ben

Steve Hunter
Steve Hunter
57,712 Points

OK - so how is the user prompted to enter the date - is that some front-end GUI? It may be better to add validation there in the form of a regular expression, or such like, rather than writing incorrect data to the back end and testing for that when you pull the wrong data out again. It strikes me that the point of entry is the bit that needs parsing for correctness.

Regular expressions are great but they are not written to be easily understood! There's a couple of sites:

http://www.regular-expressions.info/dates.html http://www.labnol.org/internet/regular-expressions-forms/28380/

Steve.

1 Answer

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

You can test that the description isn't empty, perhaps?

let date = NSDate()
date.description != ""  // this evaluates to true - for your if statement

I think a valid date will have a description which is a text representation of the date. So it'll never be an empty string.

I hope that makes sense!

Steve.

Ben Barry
Ben Barry
491 Points

That still does not work, but I probably did not give you enough information to answer it. So basically I have a NSDate that gets saved as Core Data attribute. When fetching the saved date, I want to make sure that the date is actually there before formatting it as a string to show up on the UI.

but doing the if(date.description != "") Still evaluates to true even if it does not exist in the core data fetch.

Thanks,

Ben

Steve Hunter
Steve Hunter
57,712 Points

OK - so what are the options? Is it either an NSDate or nil or can it be something else?

Is testing it at the point of writing to the Core a better option? Can you validate the entry in the store?

Sorry, but this isn't my area at all! I'm probably talking nonsense.

Steve.