Twitter blames Apple for 4 million user drop
Mr. Noto said during the company's quarterly earnings report,
So we said we lost four million monthly active users due to the iOS 8 integration. One million of those monthly active users were Twitter owned and operated monthly active users. And three million were on Safari, what we call auto-pulling MAUs, and we lost those. We don't expect to get the three million auto-pulling MAUs in Safari back, and that's a non-Twitter owned and operated auto-pulling MAU.
Translated into normal-speak, Mr. Noto is referring to a feature in iOS 7 where Safari would automatically check your Twitter account to populate the mobile browser's Shared Links tab. In iOS 8, that auto-polling doesn't happen. Twitter was counting those auto-polls in iOS 7 as active users, which likely wasn't an accurate representation of actual active users.
Mr. Costolo noted that Twitter has been working on fixes so it can get those users back, but that a single “one-size-fits_all” strategy isn't going to resolve the issue, according to Mashable.
Since iOS 8 doesn't handle Mobile Safari's Shared Links feature in the same way, Twitter essentially lost out on 3 million free stats for its quarterly active user count. From Mr. Costolo's perspective, that's a bug, not accurate metrics.