Compare two array to get index of containing object

Question

Its really a simple question but I want a short way to compare two array to get index of containing object. For example we have two arrays....

NSArray *array1=@[@"b",@"a",@"c"];
NSArray *array2=@[@"c",@"b",@"a"];

After comparison from array2 to array1, I want the index of the containing object in array1.

I tried to check the this link but I didn't get ans as I expected Fastest way to check if an array contains the same objects of another array

Answer 1

For getting indexes of objects in array1 which are also present in array2, you can use:

NSIndexSet* indexes = [array1 indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
    return [array2 containsObject:obj];
}];
[indexes enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) {
    NSLog(@"Index is %u", idx);  //do whatever you need to do with the index
}];

Answer 2

Use following method to get compare index from array 1 :

    NSMutableArray *arrayFirst = [[NSMutableArray alloc] initWithObjects:@"b",@"a",@"c", nil];
    NSMutableArray *arraySecond = [[NSMutableArray alloc] initWithObjects:@"c",@"b",@"a", nil];
    NSMutableArray *arrayComparedIndex = [[NSMutableArray alloc] init];

    for(int i =0; i<[arrayFirst count]; i++)
    {
         if ([arraySecond containsObject:[arrayFirst objectAtIndex:i]])
         {
                NSLog(@"index - %d",i);
                [arrayComparedIndex addObject:[NSString stringWithFormat:@"%d",i]];
        }
    }
    NSLog(@"arraythree - %@",arrayComparedIndex);

Answer 3

for (int i = 0; i < array1.count; i++) {
        NSString *s = array1[i];
        NSInteger anIndex = [array2 indexOfObject:s];

        NSLog(@"Index of %@ is: %d", s, anIndex);

        if (NSNotFound == anIndex) {
            NSLog(@"not found");
        }
    }