How do I add/edit the date taken and location data for old digital photos on macOS or iOS?

[iMore Question]

I recently imported all my old digital photos into Photos.app on my Mac (latest macOS installed). Most of them don't have the Date Taken or Location in the exif data. I am looking for a solution to add this data so that any app (Photos, dropbox, Flickr, etc.) can read it.
I tried editing the information within Photos.app but it does not apply outside Photos.app.
Does anyone know of a solution to fix this?
Thanks in advance

 

[Tartarus]

I use ACDSee for that purpose, but on a windows computer.

Try out one of these programs for Mac: https://www.google.nl/search?q=exif+editor+mac&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari