Question

I’m working to create a minimal MonoTouch binding for the Applifier Obj-C API. It contains this method for init:

+ (Applifier *)initWithApplifierID:(NSString *)applifierID withWindow:(UIWindow *)window 
supportedOrientations:(UIDeviceOrientation)orientationsToSupport, ...NS_REQUIRES_NIL_TERMINATION;

Following the instructions in the binding docs for variadic parameter methods, I came up with this interface method:

[Static]
[Export ("initWithApplifierId:withWindow:supportedOrientations:"), Internal]
void InitWithApplifierId (string applifierID, UIWindow withWindow,
    UIDeviceOrientation supportedOrientations, IntPtr orientationsPtr);

and this public method in my extension

public static Applifier InitWithApplifierId(string applifierId, UIWindow window,
    params UIDeviceOrientation[] supportedOrientations)
{
    if (supportedOrientations == null)
        throw new ArgumentNullException ("supportedOrientations");

    var pNativeArr = Marshal.AllocHGlobal(supportedOrientations.Length * IntPtr.Size);
    for (int i = 1; i < supportedOrientations.Length; ++i) {
        Marshal.WriteIntPtr (pNativeArr, (i - 1) * IntPtr.Size,
            supportedOrientations[i].Handle);
    }

    // Null termination
    Marshal.WriteIntPtr (pNativeArr, (supportedOrientations.Length - 1) * IntPtr.Size,
        IntPtr.Zero);

    Applifier.InitWithApplifierId(applifierId, window, supportedOrientations[0],
        pNativeArr);
    Marshal.FreeHGlobal(pNativeArr);
}

However, UIDeviceOrientation is an enum instead of an object, so there is no Handle to write. I’m very new to objective-c and fairly new to C# (my project actually interfaces with MonoTouch through IKVM; my expertise is in Java). I took a stab at doing a naive Marshal.WriteInt32 of the supportedOrientation[i] itself, but that also failed at compile time.

If it would be easier, there is an overload of this method that I could bind instead:

+ (Applifier *)initWithApplifierID:(NSString *)applifierID withWindow:(UIWindow *)window 
supportedOrientationsArray:(NSMutableArray *)orientationsArray;

However, I’m not sure how to bind NSMutableArray either 🙂

Answer 1

One solution is to bind the second method you highlight

[Static]
[Export ("initWithApplifierID:withWindow:supportedOrientationsArray:")]
Applifier InitWithApplifierID (string applifierID, UIWindow withWindow, NSMutableArray orientationsArray);

And now you can use that ctor like this

NSNumber faceDown = NSNumber.FromInt32( (int) UIDeviceOrientation.FaceDown);
NSNumber faceUp = NSNumber.FromInt32( (int) UIDeviceOrientation.FaceUp);
NSNumber landscapeLeft = NSNumber.FromInt32( (int) UIDeviceOrientation.LandscapeLeft);
NSNumber landscapeRight = NSNumber.FromInt32( (int) UIDeviceOrientation.LandscapeRight);
NSNumber portrait = NSNumber.FromInt32( (int) UIDeviceOrientation.Portrait);
NSNumber portraitUpsideDown = NSNumber.FromInt32( (int) UIDeviceOrientation.PortraitUpsideDown);
NSNumber unknown = NSNumber.FromInt32( (int) UIDeviceOrientation.Unknown);

NSMutableArray orientationsArray = new NSMutableArray(7); // Set here the number of orientations wanted

orientationsArray.AddObjects( new NSObject[7] { faceDown, faceUp, landscapeLeft, landscapeRight, portrait, portraitUpsideDown, unknown } ); // add here the orientations wanted


var applifier = Applifier.InitWithApplifierID(applifierID, withWindow, orientationsArray);

kinda ugly but should work, hope this helps

Alex