Yes, it is possible to run the game cross platforms.
The easiest way is to register you email with EA (and get 100 gems for free) on the old device, which, in your case, the Samsung phone. Do make a note or screenshot of your player ID for record just in case you need further assistance from EA. After this, you will just need to install PVZ2 to the new device, in your case the Apple iphone, do ensure you set your age to 18+ (for the cloud button to appear), then click on the cloud button to register your email again, you will then be given a choice to load your old account with the game saved progress via email verification over to the new device.
Hope this helps.
