If you've upgraded to Photos for Mac and you're running OS X Yosemite or later, you should have no problem syncing your Mac's images to your iPhone or iPad.
- Launch the Photos app.
- Click Photos on the top left of your screen and select Preferences.
- Make sure the iCloud Photo Library option is checked.
You'll likely have to wait a little bit for your Mac's images and videos to sync with your iOS devices, but afterward — assuming you have the storage space — you should have all your Mac's images accessible to you on your iPhone or iPad.