Web views are an incredibly convenient way to handle in-app browsing. Since they're WebKit, you get the same kind of experience and performance as Safari, but you don't have to send people hurtling out of your app and into Safari simply to show them a link. However, web views can't store cookies, so logins can't persist, and having to login to a web view isn't good from a security perspective anyway. So what's the solution? A "Safari view controller", according to Bryan Irace:
It'd be wonderful if Apple provided a "Safari view controller" that developers could present directly from within their applications. This controller would run out of process and work almost exactly like MFMailComposeViewController and MFMessageComposeViewController already do for composing emails and text messages respectively. The app would provide the controller with a URL (and optionally, a tint color), but otherwise what the user does in it would remain secure and isolated from any third-party code, yet fully integrated with Safari.app and Safari controllers presented by other applications.
I'm not technically adept enough to properly weigh the ramifications of this, but as a customer, having secure web views is tremendously important to me. If I'm in Twitter or Facebook or any app, and I need to login, I want to be able to do it securely — so only the website ever gets my credentials — and persistently.
Given Apple's focus on security and privacy, it seems like something they might be into for iOS 9. Fingers crossed.
For reference, this request has been filed as rdar://19205852