Which one is correct?
The patterns swam before her eyes.
OR
The patterns swam in front of her eyes.
I know that "before" is mostly used when we talk about the time, but is it right to use "before" when we talk about space? I'm most interested in spoken usage.
Certainly. The ways in which prepositions are used in English - and probably in other languages - are numerous and often bewildering. I was about to add idiosyncratic, but there is probably a logical explanation behind even the most idiomatic usages, perhaps lost in time. Some grammarians have said that prepositions constitute a class of words both semantic and functional. Prepositional usages are sometimes graded:
central (locative, directional; temporal) (eg on the bed, to the park; before midnight)
semi-idiomatic (eg on the train, at a loss)
peripheral (eg on fire)
As you suggest, before has a locative sense, synonymous with the three-word (sometimes termed 'complex') preposition in front of. Using the word idiomatic in its other main sense now (in common use in the common register), in front of is the more idiomatic of the two choices - before sounds rather poetic, of a slightly refined register.
These are synonyms do represent two different ideas:
I stand in front of the court.
And
I stand before the court.
The first implies location and direction while the other implies "in the presence".
Similarly,
before my eyes
Implies presence while
In front of my eyes
Implies location. The former would mean that it happened and you were participant if only as an observer. The latter implies that there was something flitting around (think fly, blindfold, or glasses).
Should also note: you'd generally not say, "before" unless it is in the context of people (or animals). "Before the chair" implies time or direction along a route (there is also a sense of "after" in both cases).
Prepositions have metaphorical uses that derrive from abstract meaning, as in "to be on duty", that doesn't exactly mean the same as "the book is on the table", or as in "to be under oath", that doesn't mean exactly the same as "to be under the table".
However, if you think in abstract terms, "on duty" lies on a "time table", time being the support necessary to what you do on duty, and "under oath" implies that what you say or do is submitted to an authority "above" you.
Now if you put friendship before money, it doesn't mean that you do something before another, but that you prefer friendship to money, and that friendship comes first in the order of values, rather than in the order of time, although there is a time of comparison : the first value is compared to the second.
The verb "prefer" carries the same idea : from Latin "prae" (before, in front) and "ferre" (put, set), so you can say "I prefer friendship to money" or "I put friendship before money". It also means that you put the first value above the other.
Similarly, if you appear before a judge it means that you appear before the eyes of an authority that is above you. So you might be "in front of the judge" but is isn't the same as being "before the judge" or "before a court".
You might also say "I'm in front of a house", but it doesn't mean the same as "I stopped before a large white house". The second implies that you're under the spell of its beauty.
BEFORE is far more subjective than IN FRONT OF. That's why you can be submitted to feelings when something appear before your eyes or submitted to authority if you appear before a judge.
Although grammatical and found in earlier writings, I would not suggest using before where it's possible to use in front of in this context -- except when you use an idiomatic expression.
In front of is much clearer; before used in a spatial rather than temporal sense is not very common today.
"Before" is simply more efficient. In good English, I believe "less is more"—so why use three words when one will do?
