LinkedIn drove me crazy for a long time. I hated the way you could not send a personalized connection request on their mobile apps. I have written here before about the importance of sending a personal message and being human on LinkedIn.
How to send a custom LinkedIn connection request message on mobile
I am happy to report that issue has been solved in the current version of the LinkedIn Connected application.
To send the message click the three dots on the top right corner of the person's profile. You'll be given an option to send a customized invite. You can also forward their profile if you choose.
This is your chance to send them a friendly reminder of where you met and what you talked about. Be specific, so they will remember who you are. Don't forget to include a call to action in the message. Schedule a coffee, lunch or a phone call.
LinkedIn Star List
In the latest update of the iOS app (Version 2.4), you can now add a star to contacts that matter most to you. LinkedIn will give you more opportunities to keep in touch. The app note mentions this feature may not be available straight away, but should be rolled out fully soon.