There is a bug of libdispatch on my APP, which is similar to this post, but it's on iOS across versions from 13.x to 16.x. Now I downloaded the opensource code of libdispatch from here, and I want to look into the details of source code to figure out the root cause. How can I know the branch or commit of the libdispatch code the specific iOS version (like 15.6.1) uses. crash_info_0 BUG IN CLIENT OF LIBDISPATCH: Unexpected EV_VANISHED (do not destroy random mach ports or file descriptors) fault_address 0x0000000001a37b9bc4 mach_code 0x000000000000000001 mach_subcode 0x0000000001a37b9bc4 name EXC_BREAKPOINT (SIGTRAP) reason EXC_BREAKPOINT EXC_ARM_BREAKPOINT fault_address:0x00000001a37b9bc4 type MACH_Exception 0 libdispatch.dylib __dispatch_source_merge_evt.cold.1 (in libdispatch.dylib) +36 1 libdispatch.dylib __dispatch_source_merge_evt (in libdispatch.dylib) +192 2 libdispatch.dylib __dispatch_event_loop_merge (in libdispatch.dylib) +144 3 libdispatch.dylib __dispatch_workloop_worker_thread (in libdispatch.dylib) +392 4 libsystem_pthread.dylib __pthread_wqthread (in libsystem_pthread.dylib) +284 5 libsystem_pthread.dylib _start_wqthread (in libsystem_pthread.dylib) +4 By the way, what's the difference between "__dispatch_source_merge_evt.cold.1" and "__dispatch_source_merge_evt"

Hello everyone, Are there any APIs on iOS to resolve DNS via Cellular network when WiFi is also connected? As I connect my iPhone to WiFi, DNS will be resolved via WiFi not Cellular. Low level APIs are preferred. Thanks!