Sort Array of Dictionaries by NSDate - iphone

Question

I have an array of dictionaries. Within each dictionary, there is a a key dateOfInfo (an NSDate) and several other things. I want to sort the array by each dictionaries dateOfInfo with the most recent being the first result.
How can I do this?

Answer 1

You can sort using NSSortDescription, e.g.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey: #"dateOfInfo" ascending: NO];
NSArray *sortedArray = [array sortedArrayUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
You can also use the method
- (NSArray *)sortedArrayUsingFunction:(NSInteger (*)(id, id, void *))comparator context:(void *)context

Answer 2

The basic bubble sorting algorithm would work. In this case you need to loop through your array, use valueForKey message on [array objectAtIndex:] to get the NSDate values. For comparing dates see this post . So if you are sorting in ascending order of date, just add the object with the lower date (remember bubble sort comparisons?) to an array which will hold your sorted result.

Answer 3

try like this,
NSDateFormatter *fmtDate = [[NSDateFormatter alloc] init];
[fmtDate setDateFormat:#"yyyy-MM-dd'T'HH:mm:ss"];
NSComparator compareDates = ^(id string1, id string2)
{
NSDate *date1 = [fmtDate dateFromString:string1];
NSDate *date2 = [fmtDate dateFromString:string2];
return [date1 compare:date2];
};
NSSortDescriptor * sortDesc1 = [[NSSortDescriptor alloc] initWithKey:#"StartTime" ascending:YES comparator:compareDates];
[youArray sortUsingDescriptors:#[sortDesc1]];