Set objectForKey in mutable array

NSMutableArray *nearby = [[NSMutableArray alloc]init];

[nearby addObject:[mutableArray objectAtIndex:x]];

            

[[nearby objectAtIndex:x] setValue:[NSNumber numberWithFloat:distance] forKey:@"Km"];

Sort mutableArray according to the "Km" with accending

NSSortDescriptor * sort = [[NSSortDescriptor alloc] initWithKey:@"Km" ascending:YES];

NSArray *sa = [nearby sortedArrayUsingDescriptors:[NSArray arrayWithObject:sort]];