Apple phones always have SMS reminders.

The solution of Apple's mobile phone's repeated reminder of SMS: It may be caused by turning on the "repeated reminder" function. In Settings-Notification-Information, just turn off the "Repeat Reminder" function at the bottom. After closing, whether you check the new information or not, this new information will only ring to remind you once. If this function is enabled, as long as you don't view this new message, the phone will ring repeatedly to remind you to view the message.