When attempting to open a non-existent file on an iOS device, I observed inconsistent return values between the open function from the standard libc library and the kernel syscall (syscall number 5). While the libc open function returns -1, as expected and documented, the kernel syscall open function unexpectedly returns 2. This discrepancy necessitates clarification and documentation to understand the underlying behavior and ensure predictable results when working with file I/O operations in iOS.