That depends entirely on whether you were educated before the Canadian Press Manual of Style declared "ize" to be their preference. They weren't nearly as successful with the or/our thing, but folks of my vintage or older almost always use "ise" while kids (from my perspective, thirty-somethings are "kids") only slightly favour "ize" -- and that's probably just to get rid of the damned squiggles from the spell-checker. (The rule of thumb is derived from exercice/exercise -- the noun form ends in "ice", a noun, the verb in "ise", which contains "is". I believe we Canadians are the only bunch who actually used the "ice" spelling to any degree, and it was primarily in the context of exercices at the ends of textbook chapters, which one duly carried out in an "exercice book" -- call it a notebook if you aren't a fifty-ish -year-old Canadian.) There has yet to be created an app that ships with a proper Canadian English spelling dictionary -- I have a text file that contains nothing but words that get flagged by either US or UK English dictionaries but are, and have been, standard Canadian spellings. Open it in the current nightmare app with the best-fit dictionary (US, UK, Canadian or generic English) and blindly click "add" till the prompt finally goes away.