It's definitely not that.
What's not what? Phonemically, that's how those words are analyzed. Phonetically, as has been mentioned, it's true that /i:/ for many speakers of Swedish isn't exactly [i:]; it should also perhaps be noted that English /i(:)/ often isn't [i:] either - nor is it identical to the Swedish phoneme - so it might not be a good reference point (depending on which dialect or even idiolect of either language we're talking about, though).
However, if you just want to speak understandable Swedish, this is all unnecessary hair-splitting. You can safely use [i:]; quite a lot of native speakers use something reasonably close to that as well. Not that there's anything wrong with wanting to study the phonetics in more depth, though, I guess - in which case the link Ceresz provided looks like it could be a good starting point. And if you want more, you can apparently find quite a lot of similar stuff by googling something like "phonetic analysis of Swedish vowels".
What I hear is [hɛ̯e:], [vi̯ɪ] and [nɨi̯]. I may be wrong, though.
<hej> is most definitely not [hɛ̯e:].
Yeah, that's what I would've thought, too - but listening to that sound sample on Wiktionary, I can't really say that's an unreasonable analysis.
I might say the offglide reaches as high as [ɪ], but there's certainly no audible [j] in that particular sample.
The sample for ni
is also kinda weird: if I didn't know better, I'd transcribe that as [nïi̯ç].
There's also a weird buzzing quality in the sample for vi
, but phonetically, it seems to be quite simply [vi], maybe with a very slight lowering offglide.
My conclusion would be that those samples on Wiktionary are probably not the best way to get an idea of how Swedish speakers actually usually pronounce those words in normal speech. The rather poor sound quality (and in my case, the fact that I'm listening to these in the middle of the night with low volume on laptop speakers since I left my headphones in Tartu
) doesn't help, either.