iOS Sort Array of Specific Strings

Question

I have an array of strings like such:

NSArray *unsortedArray = [NSArray arrayWithObjects:@"MailIn", @"Branch", @"eSign", @"RDC", nil];

I receive this array and it is not gauranteed that all 4 strings will be present. It could have all 4, or only 1.

I need to sort the array in this exact order all the time.. [eSign, RDC, Branch, MailIn]. Keep in mind that there is a chance where one or more of these may not be present. How do I achieve this?? Any help would be greatly appreciated. Thanks in advance!

TomSwift · Accepted Answer · 2015-07-22 20:33:14Z

2

If you really want a sort then here is a way to do that. But for only 4 strings I'd likely just unroll @Zev Eisenberg's loop and build it up in code.

NSDictionary* indexes = @{ @"eSign" : @0, @"RDC" : @1, @"Branch" : @2, @"MailIn" : @3 };
NSArray* sorted = [unsorted sortedArrayUsingComparator: ^NSComparisonResult(NSString* s1, NSString* s2) {

    return [indexes[s1] compare: indexes[s2]];
}];

answered Jul 22, 2015 at 20:33

TomSwift

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1 Comment

Zev Eisenberg Over a year ago

I like that this is O(n) instead of O(n * m) (or thereabouts), so it will scale better with a larger data set. I would still build the dictionary out of an array, though, so you don't have to type the number for each entry by hand: for (NSUInteger i = 0; i < exemplar.count; i++) { indexes[@(i)] = exemplar[i]; }.

Zev Eisenberg · Accepted Answer · 2015-07-22 20:23:37Z

1

I would build a new array, using the exemplar array as a template:

NSArray *exemplarArray = @[ @"eSign", @"RDC", @"Branch", @"MailIn" ];
NSArray *unsorted = @[ @"MailIn", @"Branch", @"eSign", @"RDC" ];

NSMutableArray *sorted = [NSMutableArray array];
for (NSString *string in exemplarArray) {
    if ([unsorted containsObject:string]) {
        [sorted addObject:string];
    }
}
NSLog(@"%@", sorted);

answered Jul 22, 2015 at 20:23

Zev Eisenberg

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