MonoTouch native crash calling CGPDFDictionary.GetArray

Question

here are the 5 lines trying to get informations about some random PDF:

        MonoTouch.CoreGraphics.CGPDFDocument oDoc = MonoTouch.CoreGraphics.CGPDFDocument.FromUrl("http://www.attachmate.com/NR/rdonlyres/C7BBC53C-CF9B-4C9C-AC3F-6C166526EC12/0/IDC_Attachmate_NetIQOverview2007.pdf");
        MonoTouch.CoreGraphics.CGPDFPage oPage = oDoc.GetPage(1);
        MonoTouch.CoreGraphics.CGPDFDictionary oDict = oPage.Dictionary;
        MonoTouch.CoreGraphics.CGPDFArray oArray;
        bool bResult = oDict.GetArray("Annots", out oArray);

Last line (oDict.GetArray()) crashes like this:

Native stacktrace:

0   Test_MT1                            0x000d1965 mono_handle_native_sigsegv + 343
1   Test_MT1                            0x0000ffb4 mono_sigsegv_signal_handler + 322
2   libSystem.B.dylib                   0x94a9705b _sigtramp + 43
3   ???                                 0xffffffff 0x0 + 4294967295
4   CoreGraphics                        0x01055068 compare_key + 34
5   libSystem.B.dylib                   0x94a5f63d bsearch + 41
6   CoreGraphics                        0x010552a1 CGPDFDictionaryGetObject + 74
7   CoreGraphics                        0x010553fa CGPDFDictionaryGetArray + 31
8   ???                                 0x0ca253f6 0x0 + 211964918

Any hints ?

Answer 1

It's not your fault, this is a MonoTouch bug.

CGPDFDictionary is being created with the CGPDFPage handle (while it should have been created with a call to CGPDFPageGetDictionary on the CGPDFPage handle).

You can workaround this bug by adding the pinvoke in your app:

[System.Runtime.InteropServices.DllImport ("/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics")]
private static extern IntPtr CGPDFPageGetDictionary (IntPtr pageHandle);

and the creating the dictionary yourself:

IntPtr handle = CGPDFPageGetDictionary (oPage.Handle);
    MonoTouch.CoreGraphics.CGPDFDictionary oDict = new MonoTouch.CoreGraphics.CGPDFDictionary (handle);