I think one of my favorite approaches is reaching out to the individuals pirating the software. Post a comment on the page explaining that you are the developer of the program. Explain why you made the application and that, if people download and enjoy it, you would appreciate them supporting future development by purchasing the application through the AppStore.
You really can't stop people from pirating your application, but you might be able to convert a few would-be pirates just by reaching out to them with your story. It's easy to steal a piece of software from a nameless entity, but it's much harder when there is a human element involved.
Going into "legal mode" rarely solves these problems because it just puts people on the defensive (and this is coming from a lawyer).
You really can't stop people from pirating your application, but you might be able to convert a few would-be pirates just by reaching out to them with your story. It's easy to steal a piece of software from a nameless entity, but it's much harder when there is a human element involved.
Going into "legal mode" rarely solves these problems because it just puts people on the defensive (and this is coming from a lawyer).