*Catalan is the only official language in Andorra and it is co-official with Spanish in the Spanish autonomous regions of Catalonia, Valencia, and the Balearic Islands. It is also spoken, with no official recognition, in a small part of the autonomous regions of Aragon (in la Franja) and Murcia (in el Carxe) in Spain, as well as in the city of Alghero on the Italian island of Sardinia and in the historic Roussillon region of southern France (usually called ‘Northern Catalonia’), roughly equivalent to the current département of the Pyrénées-Orientales.

There are two main groups of dialects, running from north to south: Eastern Catalan (Central, Balearic, Algherese, and Northern) and Western Catalan (North-western and Valencian).

Carbonell, Joan F.; Llisterri, Joaquim (1999), "Catalan", Handbook of the International Phonetic Association: A Guide to the usage of the International Phonetic Alphabet, Cambridge: Cambridge University Press, pp. 61–65, ISBN 0-521-63751-1

Positional information and geminates after discussion JK with MRL and CPM.
Note that there are two diphthongs /ju/ and /iw/ which "hidden" behind the representation /iu/, since UPSID uses only vowel symbols in diphthongs and does not show which of the two vowels is nuclear. (This is always the closest vowel, but in the case of /iu/ both vowel parts are equally close.
Likewise the two dipthongs /wi/ and /uj/ are "hidden" behind the representation /ui/.
This is clearly a shortcoming of L1-L2map and UPSID.

Sons del català: http://www.ub.edu/sonscatala/web2008.
Guiès de pronunciació del català: https://www.guiesdepronunciacio.cat.