To the OP: What kind of apartment are you referring to? Is it low-rise buildings (1-2 storey) or high-rise? If it's a high-rise (condominium), then there's no problem. But if you plan on building an apartment complex, or own a low-rise apartment complex, then you will encounter obstacles. I attended a seminar some years back (and it was also taught in college social studies) that foreigners are not allowed to own real estate in the Phils.
Upon googling, I've confirmed it. Foreigners are not allowed to own land, but they are allowed to own condominium units, provided that the maximum % of condo units sold to foreigners is 40%. There's this 60-40 rule in the Philippines. For businesses/ corporations, 60% must be owned by Filipinos, 40% by foreigners. To be considered as a corporation, there must be at least 5 incorporators. Foreigners also aren't allowed to be a sole proprietor of a business. As for land, foreigners are not allowed to own land, but can own the property (house, commercial building) built on the land. There are many proposals to amend these rulings, but as of now, they still stand.
The easiest way to go around the obstacle is to have a Filipino spouse or business partner, and have the land/business in the name of the Filipino. Many people do this, (either do marriage or set up dummy partners/corporations).
For more details, check out
Buying a House in the Philippines (or any Real Estate Property)
There's a section for a Special Resident Retirement Visa (SRRV), you must have USD 50,000 (age 50+) or USD 75,000 (age 35-49).
Philippines: Special Resident Retirement Visa (SRRV) Requirements
If you're interested in investing in condo unit(s), you can buy the unit(s) and rent or lease it/them. I don't know the ROI for that. I saw some condo units for rent/lease in Manila at airbnb.
On a personal note, I know of a Swiss national in my hometown who's married to a Filipina, and they have several 2-storey apartment units for rent.