Sorting NSString values as if NSInteger using NSSortDescriptor

Question

I have created a sort descriptor to sort a plist response coming from my server. This works well with sort key having values upto 9. With more than 10 items I see abrupt results with sort key arranged in the order = 1, 10, 11, 2, 3, 4, 5, 6, 7, 8, 9

NSSortDescriptor *aSortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"sort" ascending:YES]; self.myList = [NSMutableArray arrayWithArray:[unsortedList sortedArrayUsingDescriptors:[NSArray arrayWithObject:aSortDescriptor]]]; 

How to make it arrange in the correct order of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11?

Answer 1

You can do this by implementing a custom comparator block when creating your NSSortDescriptor:

NSSortDescriptor *aSortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"sort" ascending:YES comparator:^(id obj1, id obj2) {      if ([obj1 integerValue] > [obj2 integerValue]) {         return (NSComparisonResult)NSOrderedDescending;     }     if ([obj1 integerValue] < [obj2 integerValue]) {         return (NSComparisonResult)NSOrderedAscending;     }     return (NSComparisonResult)NSOrderedSame; }]; self.myList = [NSMutableArray arrayWithArray:[unsortedList sortedArrayUsingDescriptors:[NSArray arrayWithObject:aSortDescriptor]]]; 

See Apple documentation here

Answer 2

[list sortUsingSelector:@selector(localizedStandardCompare:)]; will sort the list in a "human" way (so "11" will come last, not between "1" and "2"). But if you really do want to treat these strings as numbers, you should make them number first!