iOS sort an NSArray of Time NSString's

Question

I need to sort an NSArray containing time NSString's such as,

NSMutableArray *times = [[NSMutableArray alloc]initWithObjects:@"09:00 AM",@"07:30 AM",@"06:45 PM",@"05:00 PM",@"12:45 AM",@"12:45 PM",@"01:00 AM",@"01:15 PM", nil];

What I need is to sort the array in ascending order of time.
Is there any way to do such a thing?

Answer 1

NSMutableArray *times = [[NSMutableArray alloc]initWithObjects:@"09:00 AM",@"07:30 AM",@"06:45 PM",@"05:00 PM",@"12:45 AM",@"12:45 PM",@"01:00 AM",@"01:15 PM", nil];

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"hh:mm a"];

NSArray *sortedTimes = [times sortedArrayUsingComparator:^NSComparisonResult(NSString *obj1, NSString *obj2)
{
    NSDate *date1 = [dateFormatter dateFromString:obj1];
    NSDate *date2 = [dateFormatter dateFromString:obj2];
    return [date1 compare:date2];
}];

optimized version:

NSMutableArray *times = [[NSMutableArray alloc]initWithObjects:@"09:00 AM",@"07:30 AM",@"06:45 PM",@"05:00 PM",@"12:45 AM",@"12:45 PM",@"01:00 AM",@"01:15 PM", nil];

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"hh:mm a"];

NSMutableArray *dates = [NSMutableArray arrayWithCapacity:times.count];
for (NSString *timeString in times)
{
    NSDate *date = [dateFormatter dateFromString:timeString];
    [dates addObject:date];
}

[dates sortUsingSelector:@selector(compare:)];

NSMutableArray *sortedTimes = [NSMutableArray arrayWithCapacity:dates.count];
for (NSDate *date in dates)
{
    NSString *timeString = [dateFormatter stringFromDate:date];
    [sortedTimes addObject:timeString];
}

Answer 2

You can try this code:

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"hh:mm a"];
    [times sortUsingComparator:^NSComparisonResult(NSString* obj1, NSString *obj2) {
        NSDate *firstDate = [formatter dateFromString:obj1];
        NSDate *secondDate = [formatter dateFromString:obj2];
        return [firstDate compare:secondDate];
    }];

Answer 3

As these are strings it will be sored as

01:15, 12:25, 05:00....

And they are not either NSDate.

So you need to do is that Create a parallel array having NSDate from these strings, sort the array, and extract these values.

---

While implementing I solved it by novice-way

NSMutableArray *times = [[NSMutableArray alloc]initWithObjects:@"09:00 AM",@"07:30 AM",@"06:45 PM",@"05:00 PM",@"12:45 AM",@"12:45 PM",@"01:00 AM",@"01:15 PM", nil];

NSMutableArray *dates=[NSMutableArray new];

NSDateFormatter *dateFormatter=[NSDateFormatter new];
[dateFormatter setDateFormat:@"hh:mm a"];

for (NSString *stringDate in times) {
        NSDate *date=[dateFormatter dateFromString:stringDate];
        [dates addObject:date];
}

NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:@"self" ascending:YES];
NSArray *descriptors = [NSArray arrayWithObject: descriptor];
NSArray *reverseOrder = [dates sortedArrayUsingDescriptors:descriptors];

[times removeAllObjects];
for (NSDate *date in reverseOrder) {
        NSString *string=[dateFormatter stringFromDate:date];
        [times addObject:string];
}

NSLog(@"%@",times);

Answer 4

For NSDate Comparison use this:

+ (BOOL)isDate:(NSDate *)date1 smallerThanAnotherDate:(NSDate *)date2
{
    NSDate* enddate = date1;
    NSDate* currentdate = date2;
    NSTimeInterval distanceBetweenDates = [enddate timeIntervalSinceDate:currentdate];
    double secondsInMinute = 60;
    NSInteger secondsBetweenDates = distanceBetweenDates / secondsInMinute;
    
    if (secondsBetweenDates <= 0)
        return YES;
    else
        return NO;
}

So If you do not want to convert your hours to NSDate do this alone it works for me

NSArray *sortedTimes =  [times sortedArrayUsingSelector:@selector(localizedStandardCompare:)];