Landscape Mode ONLY for iPhone or iPad

I want to create an application that doesn't use Portrait mode.

I am not sure if I need to edit the plist or have code in addition to the plist

Code found here

Launching in Landscape Mode

Applications in iPhone OS normally launch in portrait mode to match the orientation of the Home screen. If you have an application that runs in both portrait and landscape modes, your application should always launch in portrait mode initially and then let its view controllers rotate the interface as needed based on the device’s orientation. If your application runs in landscape mode only, however, you must perform the following steps to make it launch in a landscape orientation initially.

• In your application’s Info.plist file, add the UIInterfaceOrientation
  key and set its value to the
  landscape mode. For landscape
  orientations, you can set the value
  of this key to
  UIInterfaceOrientationLandscapeLeft
  or
  UIInterfaceOrientationLandscapeRight.

• Lay out your views in landscape mode and make sure that their autoresizing options are set correctly.

• Override your view controller’s shouldAutorotateToInterfaceOrientation: method and return YES only for the
  desired landscape orientation and NO
  for portrait orientations.

To make your app landscape mode only, you should use "Supported Interface Orientations". (Targets -> YourApp -> Supported Interface Orientations -> Landscape Left & Right)

You should also set the app's orientation in your app's Info.plist file () by appending the Supported interface orientations key with the values Landscape (left home button) and Landscape (right home button).

You may use willRotateToInterfaceOrientation and/or didRotateFromInterfaceOrientation to handle orientation changes.

shouldAutorotateToInterfaceOrientation is deprecated from iOS 6 and out.

Returning UIDeviceOrientationLandscapeLeft/Right for shouldAutorotateToInterfaceOrientation should make your app "landscape":

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return (interfaceOrientation == UIInterfaceOrientationLandscapeLeft || interfaceOrientation == UIInterfaceOrientationLandscapeRight);
}

Also may also change your app's Info.plist and View Orientation (as explained above).

Additionally, I recommend changing your view's orientation to Landscape in the Attributes Inspector.

You could also just shorten it all to

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return UIInterfaceOrientationIsLandscape(interfaceOrientation);
}

edit the plist to only support landscape, then make sure that in every uiviewcontroller/uitabbar etc., in the shouldAutoRotateToInterfaceOrientation, the return says return ((interfaceOrientation == UIInterfaceOrientationLandscapeLeft) || (interfaceOrientation == UIInterfaceOrientationLandscapeRight));.