Monotouch - View created in landscape orientation

问题:

I've created a view controller and set the orientation of the view to Landscape in XCode 4.2 (Interface Builder). However, when I add the view, the view is displayed in Portrait orientation. I've overriden ShouldAutorotateToInterfaceOrientation in all view controllers to return true, and I've attempted to rotate the view manually using the following code:

this.View.Transform.Rotate (3.14f * .5f);

I have also tried to set the frame to a landscape frame (i.e. 480 X 320), though the frame of the view is already set correctly.

Just to clarify, the vast majority of my views are in Portrait. I would like to load the landscape view in a landscape orientation, irrespective of what orientation the device is actually in. Is this possible? If so, what am I missing?

Thanks in advance for any assistance on this matter!

UPDATE: I'm noticing that ShouldAutorotateToInterfaceOrientation is only called once when the view is loaded. It is not called when the device is rotated. Is this normal behavior?

回答1:

ShouldAutorotateToInterfaceOrientation is called every time the device orientation changes.

public override bool ShouldAutorotateToInterfaceOrientation (UIInterfaceOrientation toInterfaceOrientation)
        {
            Console.Out.WriteLine(toInterfaceOrientation.ToString());
            // Return true for supported orientations

            // This particular screen is landscape only!
            return (toInterfaceOrientation == UIInterfaceOrientation.LandscapeLeft || toInterfaceOrientation == UIInterfaceOrientation.LandscapeRight);
        }

this code will only allow the view to orient itself in either landscapeleft or landscaperight mode, and writes the new device orientation to the console every time.

when you load the view, and push it onto (for instance) a UINavigationController however, it's still in portrait mode (and ShouldAutorotateToInterfaceOrientation is not called.)

From Objective-C, it's fairly easy to force a device orientation, but in MonoTouch, there appears to be no direct mapping.

the solution ;

Send a message to the objective-c runtime, specifying which orientation we want.

you can easily do this by adding the following to a view controller:

Selector orientationSetter;

        private void SetOrientation (UIInterfaceOrientation toOrientation)
        {
            if (orientationSetter == null)
            {
                orientationSetter = new Selector ("setOrientation:");
            }

            Messaging.void_objc_msgSend_int (UIDevice.CurrentDevice.Handle,
            orientationSetter.Handle, (int)toOrientation);
        }

you can now manually change the orientation of the entire device. What's more, is that if you use a UINavigationController, the orientation will return back to normal once this view is popped off the stack.

回答2:

I think that for the Landscape view that you always want to display in Landscape Orientation, you need to return False within ShouldAutorotateToInterfaceOrientation or remove the override altogether. This will prevent the view from auto-rotating when the device is in portrait mode.