Issue To install The Sims3 om Mac OS X Yosemite [SOLVED]

hi, guys.
Hope i posting my issue in right place, im new to this website.
Anyway i decided to get back into the sims 3 game, im using mac, so a bit more difficult to install game, but following descriptions i had installed it, but today my MAC got new software update OS X Yosemite and now i cant even open iso file, any ideas? what to do and how to do? i added screen shot with the message what im keep getting!

//MOVED

Hi there, and welcome to the Games4theworld Forum!

I moved your topic to Mac Support, the correct Forum for your question.

Regarding your issue, you can find some ways to bypass Gatekeeper (the protection that caused the error) here:
http://m.imore.com/how-open-apps-unidentified-developer-os-x-mountain-lion

It's for OS X Mountain Lion, but I don't see why it wouldn't work in Yosemite too.

Please, let us know how it goes. Good luck!

Hey Thank you. Its actually did helped, but i have now another issue (disgraceful) 
I am following installation by Games4theworld guide, so im trying now install season expansion, but its keeps coming this message "To install The Sims 3 Seasons you must already have the sims 3 installed"... so basically the base game is nowhere... but it is in my Applications...

Hi there,
May I know if you're downloaded the base file from games4world?
Also if you can tell me all your steps, and I can help locate if you did something wrong. Thanks

Hi, thank you, for ur replay, but i did solved in the end what i was doing wrong

Mod. edit: Therefore, I am closing the topic. Please feel free to connect with us if you have further problems
-Phoebe