Question

I’m just looking for a nicer and more efficient way to iterate through a given array of objects and compare a NSString property of each to another array just containing NSStrings.

My current code uses two for-each loops but it don’t think that it is the most efficient way.

for (MYClass *foo in arrayOfMyClass) {
    for (NSString *ID in arrayOfStringIDs) {
        if ([foo.Id isEqualToString:ID]) {
            //Do something
            break;
        }
    }
}

I think that it should be somehow possible to drop at least one loop with some cool tricks.

Answer 1

If all you want to know is if foo.Id exists in arrayOfStringIDs, use an NSSet of strings instead. Then you can do:

NSSet * mySetOfStringIDs = [NSSet setWithArray:arrayOfStringIDs];
for(MyClass * foo in arrayOfMyClass) {
    if([mySetOfStringIDs containsObject:foo.Id]) {
        // Do something
        break;
    }
}

This avoids the second loop, since containsObject: is generally much faster than O(n) for a set. You should, of course, do your own profiling as needed.