I did it simply by installing dracut $ sudo pacman -Syu dracut. After installing dracut, I used dracut to generate a kernel image first to test whether my computer can boot with the new kernel image. Once I was certain that my computer could boot with the kernel image generated using dracut, I uninstalled mkinitcpio-openswap before uninstalling mkinitcpio.
The next step depends on whether you want to stick to using grub or you want to switch to systemd-boot.
If you want to stick with Grub, you need to install the necessary pacman hooks for dracut. This can be done via sudo pacman -Syu dracut-hook.
If you want to switch to systemd-boot, you don’t have to install dracut-hook. Switch to systemd-boot by following the guide written by Dalto, and then install kernel-install-for-dracut, which contains all the hooks required for automation.