Hide Status bar in Windows Phone 8.1 Universal Apps

Solution 1:

With the release of Windows Phone 8.1 SDK comes a new StatusBar. The StatusBar replaces the SystemTray from Windows Phone Silverlight Apps. Unlike the SystemTray, the StausBar can only be accessed via code and some functionality has changed.

StatusBar statusBar = Windows.UI.ViewManagement.StatusBar.GetForCurrentView();

// Hide the status bar
await statusBar.HideAsync();

//Show the status bar
await statusBar.ShowAsync();

Reference: Differences between the new StatusBar in Windows Phone XAML Apps and the SystemTray

Msdn Reference: StatusBar class

Solution 2:

await Windows.UI.ViewManagement.StatusBar.GetForCurrentView().HideAsync(); 
await Windows.UI.ViewManagement.StatusBar.GetForCurrentView().ShowAsync(); 

for hiding and showing the system tray