IKEV2 is fast and secure and mobile-friendly VPN protocol.

Since it has no interface, it is a little complex to create.
Here are the steps:
Add CA

Sign It

Add Server Certificate

Sign It with CA

Add Client Certificate

Sign It with CA

Export CA for Clients (for iOS)

Export Client Certificate (for iOS)

Add ip pool for IKEV2 (better calculate online)

Add mode config for Ikev2

Add Proposal for Ikev2

Create Group for Ikev2

Create Policy for Ikev2
Add profile for Ikev2

Add Peers for Ikev2

Add Identity for Ikev2

Now, Ikev2 server in RouterOS is finished.
Download the exported two files, CA and CA client.
And copy to iPhone iCloud .
Install the two certificates.
Add VPN Ikev2 (it is default vpn protocol in iOS)
Done!