For the past three years, Lance Walker has been locked in a cat-and-mouse game with his 11-year-old daughter for control over her iPhone and iPad.

Initially he considered TikTok a harmless distraction, which Peyton used for watching dance videos. When he discovered she was receiving messages from adult men she didn’t know after posting public videos of herself doing silly poses, he quickly went into Apple Inc.’s parental-control settings to block access to the app. Peyton countered by using a different Apple ID to download new apps including TikTok.