It is dependent on factors listed below. You are considered a nonresident of CA if you didn't live there. According to CA FTB publication 1031, you are supposed to file a return there if you had CA-source income. As a nonresident, the CA 540NR booklet (and the previously mentioned publication) gives guidelines for if you have to file. There is a gross income test (all income sources, not just CA), adjusted gross income test, children with investment income test, and an "other situations when you must file" section. It does not state anything about being physically present, as another had mentioned. Ftb.ca.gov/forms/2018/18-540nr-booklet.html
