Representing hourly ranges in Objective-C

Question

I'm trying to create a class that represents hours of operation in an Obj-C program. I have been considering using NSDatesComponent to do this, but I feel there should be an easier way. Does anyone have any tips as to how to do this?

In Core Data, I would have a shop entity that would have an ivar that is an array. This array would have seven entries for each day of the week, and the value for each day would be an hoursOp object that would represent a range of hours. 9-5, 10-6, etc. The issue is, I'm not sure how to create my hoursOp class to represent a range of hours. I was thinking of using NSDateComponents, but am unsure if I should bother. Currently, I think that an hoursOp object should hold two variables: a starting time and an ending time.

Furthermore, this is complicated by the possible need for multiple hoursOp objects in an array entry- what if a shop has operating hours of 10-4, then 6-8? So instead of an array that holds hoursOp object, it would be a two-dimensional array where each entry is an array of its own holding 1 or more hoursOp objects. This is all a bit convoluted, but I believe I could get it to work, once I figure out how to represent the hours (or the ranges themselves, if anyone has a better suggestion).

Do you need to encode a day of the week? On what resolution? — yan, Apr 13 '11 at 20:36

score 0 · Answer 1 · answered Apr 13 '11 at 23:51

0

It's hard to say the "best" way to implement this, because it depends on what you're doing with the data, but if you stored the day of the week, opening time and closing time inside your hoursOp object, you could have a one-dimensional array of hoursOp objects that represented time intervals when the store was open.

You'd lose the one-to-one relationship between your array index and the day of the week, which might make some tasks harder (if you're constantly querying this object for its Saturday store hours, for instance, you'll be scanning the entire array a lot), but otherwise you're going down the path of having an array of arrays.

answered Apr 13 '11 at 23:51

Scott Forbes

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Fair enough. Does that mean I shouldn't bother with NSDate for representing the hours? – Apophenia Overload Apr 13 '11 at 23:54
`NSDateComponents` might be overkill, but then again fields like time zone and minutes could come in handy – I'd probably err on the side of using the built-in class, even if it does more than I (currently) need. – Scott Forbes Apr 21 '11 at 23:46

score 0 · Accepted Answer · answered Apr 29 '11 at 21:09

This is what I ended up doing, using NSDate and NSDateFormatter only, where open is an NSString formatted in military time.

-(void) setOpeningTimeWithString: (NSString *)open
{
    NSDateFormatter * formatFromInput = [[NSDateFormatter alloc] init];
    [formatFromInput setDateFormat:@"HH:mm"];
    self.openingTime = [formatFromInput dateFromString:open];   
    [formatFromInput release];  
}

The takeaway lesson is that it's perfectly okay to have NSDate objects where you only set the hourly components- everything else is only set to January 1, 1970, and it doesn't cause any issues.

Representing hourly ranges in Objective-C

2 Answers2