  Mobile applications (apps) have become deeply personal, constantly demanding
access to privacy-sensitive information in exchange for more personalized user
experiences. Such privacy-invading practices have generated major
multidimensional and unconventional privacy concerns among app users. To
address these concerns, the research on mobile app privacy has experienced
rapid growth over the past decade. In general, this line of research is aimed
at systematically exposing the privacy practices of apps and proposing
solutions to protect the privacy of mobile app users. In this survey paper, we
conduct a systematic mapping study of 54 Software Engineering (SE) primary
studies on mobile app privacy. Our objectives are to a) explore trends in SE
app privacy research, b) categorize existing evidence, and c) identify
potential directions for future research. Our results show that existing
literature can be divided into four main categories: privacy policy,
requirements, user perspective, and leak detection. Furthermore, our survey
reveals an imbalance between these categories; majority of existing research
focuses on proposing tools for detecting privacy leaks, with less studies
targeting privacy requirements and policy and even less on user perspective.
Finally, our survey exposes several gaps in existing research and suggests
areas for improvement.
