What type of connection are you using? A bridged or routed vpn? For vpn to work on iphone you need to use only routed connection(tun), tap is not supported.
Here is my config file, you can us it as a draft for your opvm.
client
dev tun
proto udp
remote YOUR ADDRESS 1194
resolv-retry infinite
nobind
user nobody
group nobody
persist-key
persist-tun
#mute-replay-warnings
<ca>
-----BEGIN CERTIFICATE-----
Open your ca certificate with a text editor and copy the strings from it here.
-----END CERTIFICATE-----
</ca>
<cert>
-----BEGIN CERTIFICATE-----
Open your client certificate with a text editor and copy the strings from it here.
-----END CERTIFICATE-----
</cert>
<key>
-----BEGIN PRIVATE KEY-----
Open your client key with a text editor and copy the strings from it here.
-----END PRIVATE KEY-----
</key>
ns-cert-type server
<tls-auth>
Open your ta key with a text editor and copy the strings from it here.
-----END OpenVPN Static key V1-----
</tls-auth>
cipher YOUR CYPHER
comp-lzo
verb 3
