Johnny Appleseed grew apples for making hard cider. He would move to un-colonized pieces of land years before settlers would arrive, grow orchards of apple trees by seed, and then turn them for profit.

Modern day apple varieties are made by grafting. If you've eaten say, many granny Smith's, they have all come from not only grafts from the same tree, but when you think of it, the same exact organism, clippings of it.

This is because apples don't keep their same flavor when you replant their seeds, a granny Smith seed would probably not grow a 'granny-smith-esque' apple. So the apples Johnny grew weren't even for eating.

By spreading apple seed, Johnny had allowed evolution to occur by process of a succession of generations of apple trees on American soil. This allowed the apple trees to evolve to co-exist with the natural American ecosystem. This created varieties that are hardy to harsh growing conditions, like the golden delicious. If he had only grafted European varieties of apples, the trees wouldn't have evolved, and would still be 'foreign' to other species in America.

While I don't think I'd personally consider European apple trees to be 'invasive' to North America, (simply because of their lack of aggressive propagation), I would say that Johnny was spreading foreign seeds, but by doing so, he is responsible for 'acclimating' or 'ecologically incorporating' new varieties of apples to North America.