Although "Veronika" is the, so to speak, official Swedish way of spelling this name, only about 1/7 of the Swedish women named so spell it with a "k". Most common is to spell it with a "c" just as in English.
The name Veronika is from these words: "Vere iko nika". Which means: "Brings the true image". Veronika also comes from name Verenika which means victory. It is very popular name in the Czech and Slovak Republics.
In Czech and Hungarian, at least, the name would be accented on the first syllable (as is everything else in these languages, though in Czech there is some dialectal variation). In Hungarian the pronunciation would be (approximately) VAR-o-nee-ka. I knew a Hungarian-born woman with this name. She said the usual nickname was Veron (pronounced VAR-on).
My mother named me Veronika (she's from Germany), and growing up, I honestly wished I had a more common name, like Lisa or Jenny. I felt strangely alone having one of the more exotic names in school, with the "K" spelling only adding to the mystique. My entire life, I've only met only 3 other Veronicas, and none with a "K". At home I was called Ronnie (my dad read the Archie comics growing up), and in high school, friends tried out different names like "Nika" and "Vero" (I hated those and never responded). For a while in college, my coworkers called me "Vernie" (horrible, but funny), and at one of my early post-college jobs, elderly customers on the phone heard my name as "Rhonda", and that stuck for a bit. As I got older, I decided I not only liked my name, but I loved the spelling. I've found when someone learns my name before meeting me, there's a tendency to assume I'm glamorous, smart, and sexy. While I won't deny these qualities, I am more nerd than sexpot.