iphone - I have an NSArray on NSString's, but some of the strings are only numbers. How do I sort numerically properly?

Question

My NSArray contains 100, 110, 91, 98, and 87, all NSStrings.

I'd like to sort them to show up in this order: 87, 91, 98, 100, 110.

Instead they are showing up as 100, 110, 87, 91, 98.

I can't start the array with all ints instead of strings unfortunately. Anyone have any ideas on how to tell if the array contains ONLY numbers from strings, maybe using a for loop? Then I could just convert them all to ints within the array and do the sort that way. Or maybe there is an easy way I am missing?

Let me know if anyone has any ideas.

Answer 1

You can use the NSNumericSearch option to the NSString compare function to sort strings numerically. To do this with an NSArray, you will need to write a block or function to call the compare:options: method.

NSArray *theStrings; // Contains strings, some of which are numbers
NSArray *theSortedStrings = [theStrings sortedArrayUsingComparator:^(id obj1, id obj2) {
    return [(NSString *)obj1 compare:(NSString *)obj2 options:NSNumericSearch];
}];

This will also sort numerically if there is a numer within a string, i.e. "abcd89" will come before "abcd123".