A feature can be disabled on the operating system of iOS in order to save data on its subscription, reports
This one is called Wi-Fi Assist and it exists on version iOS9 as well as more recent versions.
Get an idea of your consumption
This has been designed so that mobile data does not activate automatically when you receive an attachment that is too large, or an audio or video streaming is started.
This is the case when a wifi connection is particularly too weak.
It also prevents the service from being activated when roaming.
Wi-Fi Assist is in the Settings section, then Cellular.
The option is then at the bottom of the proposed list.
Information is available regarding the volume of data that was used.
This indication is intended in particular for people who consume a lot.
It allows Apple users to get a feel for the needs of their online business.
With Apple Pay Later, Apple launches into payment in several installments
Apple: Some Wi-Fi network names bug iPhone and iPad