How to compare NSDates to find earliest and latest dates in an array?

Question

I'm having a lot of problems with my code that determines the earliest date and latest date in an array. Here is the code I'm using:

NSDate *startDate = nil; // Earliest date
NSDate *endDate = nil; // Latest date

for (id entry in myArray) 
{
    NSDate *date = [entry objectForKey:kDate];

    if (startDate == nil && endDate == nil) 
    {
        startDate = date;
        endDate = date;
    }
    else if ([date compare:endDate] == NSOrderedAscending)
    {
        startDate = date;
    }
    else if ([date compare:startDate] == NSOrderedDescending)
    {
        endDate = date;
    }

    date = nil;
}

Please can someone help me work out where I'm going wrong?

Answer 1

Surely you're setting startDate and endDate the wrong way round in the else if statements? Don't you want this:

NSDate *startDate = nil; // Earliest date
NSDate *endDate = nil; // Latest date

for (id entry in myArray) 
{
    NSDate *date = [entry objectForKey:kDate];

    if (startDate == nil && endDate == nil) 
    {
        startDate = date;
        endDate = date;
    }
    if ([date compare:startDate] == NSOrderedAscending)
    {
        startDate = date;
    }
    if ([date compare:endDate] == NSOrderedDescending)
    {
        endDate = date;
    }

    date = nil;
}