Question

I have an array named ‘names’ with strings looking like this:
[“name_23_something”, “name_25_something”, “name_2_something”];
Now I would like to sort this array in ascending order so it looks like this:
[“name_25_something”, “name_23_something”, “name_2_something”];

I guess that should start of with extracting the numbers since I want that
the sorting is done by them:

for(NSString *name in arr) {
    NSArray *nameSegments = [name componentsSeparatedByString:@"_"];
    NSLog("number: %@", (NSString*)[nameSegments objectAtIndex:1]);     
}

I’m thinking of creating a dictionary with the keys but I’m not sure if that is the correct objective-c way, maybe there some some methods I could use instead? Could you please me with some tips or example code how this sorting should be done in a proper way.

Thank you

Answer 1

@implementation NSString (MySort)

- (int) myValue {
    NSArray *nameSegments = [self componentsSeparatedByString:@"_"];
    return [[nameSegments objectAtIndex:1] intValue];
}

- (NSComparisonResult) myCompare:(NSString *)other {
    int result = [self myValue] - [other myValue];
    return result < 0 ? NSOrderedAscending : result > 0 ? NSOrderedDescending : NSOrderedSame;
}

@end

...

arr = [arr sortedArrayUsingSelector:@selector(myCompare:)];