iOS7 Vs iOS8 auto layout and webview issue

I have a view controller that is composed of a web view and a toolbar with some basic controls. The toolbar is pinned to the bottom of the screen using auto layout. It has four constraints, to pin it to the left side of the screen, the right side of the screen, the bottom of the screen and another that pins the bottom of the web view to the top of the toolbar.

I am having too issues with this. The first is that the web view when loading a URL has a black bar running across the bottom of the screen for a second or two while the page loads, see attached screen shot. This occurs on both iOS7 & iOS8.

The second issue I am having with iOS7. The screen that calls this screen is the typical navigation bar inside a tab bar setup. The user presses a button to go to a particular page, the browser gets created and pushed onto the navigation bar stack. It hides the tab bar when created. In iOS8 this works perfectly, the toolbar is pinned to the bottom of the screen. In iOS7 the tab bar is removed but the toolbar is placed as if the tab bar was still present?! Any ideas how to fix these two issues? Many thanks.

FYI - Xcode 6.1.1