So cost plays an important role in the adoption of Swift as well.
However, what I learned is, if you want to leverage MIT or BSD licensed widgets, libraries and etc, Swift is where it is at. Way too many of the ObjC code available has gone fallow with iOS 8 or 9, so you can still use it now. But the writing is on the walls, sooner or later iOS 12 or 15 is going to break that code and then the ObjC choice turns into technical debt. It runs the gamut from code that isn’t AutoLayout aware, to using deprecated but still available methods. I’ve steered clear of any code that hasn’t seen an update in 18 months.
It shouldn't be a factor in the decision about using Swift or not.
(1) Time to market: how fast can you implement a “ship-able” feature, app
(2) Resource cost/availability: can you find delivery resources easily and cost effectively. Sometimes this resource is you, metric appropriately.
(3) Scalability: as you grow and features change, how do the other two things change. Do they change for the better or the worse.
The weighting of these depends on longitivtiy expectations. If your short sighted for immediate reward weigh (1) and (2) higher if your confidence is high on the outcome of what your doing then weigh (2) and (3) higher.
For this discussion Swift wins on almost all fronts. The exception might be legacy maintenance , and even then it might be a knife fight of when and how.