Open Radar

 
Area:
UIKit

Summary:
UIDevice orientation not preserved when changing the root view controller.

Steps to Reproduce:
-- In a test case --
* See attached project with the following unit test:
// Change the device orientation.
XCUIDevice.sharedDevice.orientation = UIDeviceOrientationLandscapeLeft;
XCTAssertEqual(UIDevice.currentDevice.orientation, UIDeviceOrientationLandscapeLeft);
XCTAssertEqual(XCUIDevice.sharedDevice.orientation, UIDeviceOrientationLandscapeLeft);
// Change the root view controller.
UIApplication.sharedApplication.keyWindow.rootViewController = [[UIViewController alloc] init];
// XCUIDevice orientation is preserved.
XCTAssertEqual(XCUIDevice.sharedDevice.orientation, UIDeviceOrientationLandscapeLeft);
// UIDevice orientation is NOT preserved (the following assertion fails).
XCTAssertEqual(UIDevice.currentDevice.orientation, UIDeviceOrientationLandscapeLeft);

-- In the debugger --
1) Pause program execution to enter the debugger.
2) Run the following lldb commands:
(lldb) po UIDevice.currentDevice.orientation
UIDeviceOrientationPortrait
(lldb) expr UIApplication.sharedApplication.keyWindow.rootViewController = [UIViewController new];
(UIViewController *) $3 = 0x00007fd29dc06c40
(lldb) po UIDevice.currentDevice.orientation
UIDeviceOrientationUnknown

Expected Results:
UIDevice.currentDevice.orientation should have the same orientation before and after the root view controller is changed.

Actual Results:
UIDevice.currentDevice.orientation returns UIDeviceOrientationUnknown after the root view controller is changed.

Version/Build:
Xcode v9.4.1 - v10.0 beta 5 (I didn't try earlier than v9.4.1)
iOS SDK 10.0-12 (I didn't try earlier than SDK 10)