My app may triggered a iOS bug. When the main thread is stuck, that make SpringBoard or FrontBoard reboot(apple icon displayed). I can't reproduce this bug, It does not appear often. Here is my app ips file and SpringBoard log. What's kind of code can reboot SpringBoard? SpringBoard crash log: {"bundleID":"SpringBoard","timestamp":"2021-10-12 17:09:49.00 +0800","os_version":"iPhone OS 15.0 (19A346)","incident_id":"E43F8A0A-6998-4558-8F59-C695E89A5109","share_with_app_devs":0,"bug_type":"309","app_name":"SpringBoard","name":"SpringBoard"} { "deployVersion" : 210, "variant" : "stackshot", "incident" : "E43F8A0A-6998-4558-8F59-C695E89A5109", "crashReporterKey" : "0548738900860e9e93c4d190f1e06ad255ec3849", "modelCode" : "iPhone12,1", "cpuType" : "00000000", "osVersion" : { "train" : "iPhone OS 15.0", "build" : "19A346", "releaseType" : "User" }, "variantVersion" : 2, "captureTime" : "2021-10-12 17:09:49.7257 +0800", "pid" : -1, "procName" : "SpringBoard", "bundleInfo" : {"CFBundleIdentifier":"SpringBoard"}, "termination" : {"flags":0,"indicator":"monitoring timed out for service","code":1,"namespace":"WATCHDOG","details":["(1 monitored services unresponsive): checkin with service: SpringBoard returned not alive with context:","unresponsive dispatch queue(s): com.apple.main-thread","60 seconds since last successful checkin, 427 total successsful checkins since wake (0 induced crashes)"]}, Thank for help log.crash