Fout Tip K ?

[BSBAL18]

Every game you will probably see a batter swing with 2 strikes and foultip it directly into the catchers mit... Strikeout. However, my question is, batter ducks to get out of a ball thrown around his head, the bat stays up and the ball hits the bat and subsequently goes straight to catchers mit.

Does the rule state the batter *must attempt* or engage at the ball for the foul-tip strike 3? Or since it was technically a foultip, the result of the play is a strikeout?