There are plenty of reasons why you might be paying special attention to your iPhone’s consumption of data over its cellular connection. Maybe you’re on a restrictive plan and pushing the limits of your allocated bandwidth, or perhaps you’re roaming internationally and would like to avoid what can be some very steep rates. Luckily for you, there are tools to help to manage how and when you use data, like the setting built-in to the App Store that lets you control whether downloads occur over your phone’s 3G connection, or if they should be saved for when you’re getting online via WiFi. At least, that’s how it’s supposed to work, though some testing shows that this setting may not be behaving the way you’d expect it to.
For downloads over 20MB, the phone will always wait until you’re connected over WiFi to retrieve them, and this setting is supposed to give you that same option for smaller files. In practice, though, your preference apparently readily gets ignored. Tests have shown both initial downloads and app updates preceding unhindered when both WiFi was disabled and this option not to use cellular data enabled.
Are users just misinterpreting what Apple’s intent was for this setting to do? We’d love to hear something from the company about it, but apparently it’s yet to follow-up with those who have reported the issue. For now, we’ll just have to keep a close eye on our data usage.