Sorting NSArray which many contain number

Question

I have an NSArray which is populated with objects from an NSMutableArray. Most of these object have integer values like "1", "2", "3", "4", "5", sometimes there is a name like "home", "far left", or "far right". I am trying to sort this array in Objective C. using sortedArrayUsingSelector:@selector(compare:) works fine when I have less then 10 items in the array. but when it there are more I start getting "1", "10", "11", "12", "2", "3" type of stuff. Any help would be most appreciated. The code should not return anything. It just needs to sort and move on.

Original Code:

presetNamesSort = [[[NSMutableArray alloc]init]retain];

presetNamesSort = [presetNames sortedArrayUsingSelector:@selector(compare:)];

Answer 1

You can use NSArray's -sortedArrayUsingComparator: method to get a sorted array using a custom block. I find this more convenient than -sortedArrayUsingSelector:, because you can declare the comparator inline, like so:

NSArray *unsortedArray = [NSArray arrayWithObjects:@"Hello", @"4", @"Hi", @"5", @"2", @"10", @"1", nil];
NSArray *sortedArray = [unsortedArray sortedArrayUsingComparator:^(NSString *str1, NSString *str2) {
    return [str1 compare:str2 options:NSNumericSearch];
}];

This will return an array that looks like so:

(
    1,
    2,
    4,
    5,
    10,
    Hello,
    Hi
)

In general, it's pretty nice to use blocks because they eliminate the need to create random selectors that run amuk in your code.

Answer 2

try using -[NSString compare:options:] with NSNumericSearch. To use that with -sortedArrayUsingSelector: you have to wrap the compare call into a separate category method on NSString:

- (NSComparisonResult)numericCompare:(NSString *)aString {
    return [self compare:aString options:NSNumericSearch];
}