Particulary i was 3 weeks without iPhone. At that time i had only apple watch where i tried several apps if works without iphone. For sure there were no e-mail client who would work independtly nor any twitter client . From native apps only weather was showing me realtime weather, all other apps internet depended did not worked (e-mail client, messages etc) also calendar for example fantastical 2 stop remind me regarding events. in tis respect i wanted to know which apps in no particular order are truly independent apps which works completely without iPhone and still update data after couple of days of no usage of IPhone. Just record is not so good example as you dont need internet to record voice.