Do I need .dmg files?

Question

I have packaged my mac application into a .dmg file, but when I mount the file and double click on it, I get this warning. "MyApp is an application downloaded from the Internet. Are you sure you want to open it ?."

I do not want my application to look suspicious. I know that on Windows you need to sign your installer so that the OS does not display the frightening red stop icon and the “Unverified” / “Unknown” label, the same for OS X?

Answer 1

No, you will always receive this notification when you first start everything that you downloaded. This is a flag set to extended file attributes.