The timing of your question could not be better, as the United States Supreme Court heard oral arguments on this very issue (cell phone searches in general) just today. The simple answer is no one knows.
In a little more depth, the answer is probably if 1) you are on supervision, because "conditions of supervision" are executed at the iutset of probation giving up a lot pf rights, particularly 4th Amendment rights, & 2) children, unfairly, do not seem to have the same consltutional rights as adults. I have never understood why. It is, nonetheless, a fact.