I'm using Chris Branson's RedLaser MonoTouch bindings and sample from here: https://github.com/chrisbranson/RedLaserSample
Firstly, to help out those also having trouble with this sample project, I had to update both the makefile to build the RedLaser.dll MonoTouch bindings and the sample MonoDevelop csproj to get the actual app compiling.
Makefile
The makefile supplied by Chris unzipped the RedLaser SDK download, but RedLaser changed their naming convention and so it was no longer working. I simplified it, instead requiring the user to put the libRedLaserSDK.a file into the build directory manually:
BTOUCH=/Developer/MonoTouch/usr/bin/btouch
BUILDVER=build139
VERSION=3.2.4
BINDIR=./bin/
all: $(BINDIR)RedLaser.dll
$(BINDIR)libRedLaserSDK.a:
@echo "You'll need to obtain a copy of RedLaserDevSDK-$(VERSION).zip from"
@echo "http://redlaser.com/sdk/index.php"
@echo Locate the libRedLaserSDK.a file and place within
@echo $(BINDIR)
@echo
@open http://redlaser.com/sdk/index.php
@exit 1
$(BINDIR)RedLaser.dll: Makefile AssemblyInfo.cs RedLaser.cs enums.cs $(BINDIR)libRedLaserSDK.a
$(BTOUCH) --out=$@ -e RedLaser.cs enums.cs AssemblyInfo.cs --link-with=$(BINDIR)libRedLaserSDK.a,libRedLaserSDK.a
clean:
-rm -rf $(BINDIR)*.dll
The directory containing the makefile should also contain the files redlaser.cs, enums.cs and AssemblyInfo.cs (i.e. the same as Chris's).
MonoDevelop project build settings
I think the reason this stopped working was a bug in MonoDevelop or MonoTouch and the way it expands the 'Additional mtouch arguments' when they contained quotation marks. Chris's original arguments looked like this:
-cxx -gcc_flags="-framework SystemConfiguration -framework CFNetwork -framework CoreVideo -framework CoreMedia -framework AVFoundation -framework OpenGLES -framework Security -L${ProjectDir}/Lib -lRedLaserSDK -ObjC"
MonoDevelop doesn't parse this correctly, instead inserting quotation marks around each option separated by a space. Looking in the build output (under 'Compiling to native code') showed that this got expanded to:
"/Users/tyson/Downloads/chrisbranson-RedLaserSample-1a5545f-1/RedLaserSample/Lib/RedLaser.dll" -debug -nolink -sdk "5.1" -targetver "5.1" --armv7 "-cxx" "-gcc_flags=\"-framework" "SystemConfiguration" "-framework" "CFNetwork" "-framework" "CoreVideo" "-framework" "CoreMedia" "-framework" "AVFoundation" "-framework" "OpenGLES" "-framework" "Security" "-L/Users/tyson/Downloads/chrisbranson-RedLaserSample-1a5545f-1/RedLaserSample/Lib" "-lRedLaserSDK" "-ObjC\""
The solution involves adding explicit quotation marks around the whole 'gcc_flags' option, manually escaping the inner quotation marks. e.g:
"-cxx" "-gcc_flags=\"-framework SystemConfiguration -framework CFNetwork -framework CoreVideo -framework CoreMedia -framework AVFoundation -framework OpenGLES -framework Security -L${ProjectDir}/Lib -lRedLaserSDK -ObjC\""
This expands correctly into:
"/Users/tyson/Downloads/chrisbranson-RedLaserSample-1a5545f-1/RedLaserSample/Lib/RedLaser.dll" -debug -nolink -sdk "5.1" -targetver "5.1" --armv7 "-cxx" "-gcc_flags=\"-framework SystemConfiguration -framework CFNetwork -framework CoreVideo -framework CoreMedia -framework AVFoundation -framework OpenGLES -framework Security -L/Users/tyson/Downloads/chrisbranson-RedLaserSample-1a5545f-1/RedLaserSample/Lib -lRedLaserSDK -ObjC\""
Ok, so now that I had it compiling I attempted to run it on my phone. The app loads up fine, and successfully calls into the RedLaser SDK via the RedLaserSDK.CheckReadyStatus() function. But as soon as I hit the scan button (which loads the BarcodePickerController) it crashes with a native exception deep within the RedLaser SDK:
terminate called throwing an exception
Native stacktrace:
0 RedLaserSample 0x0159d62d mono_handle_native_sigsegv + 244
1 RedLaserSample 0x015b6251 sigabrt_signal_handler + 112
2 libsystem_c.dylib 0x319b67ed _sigtramp + 48
3 libsystem_c.dylib 0x319ac20f pthread_kill + 54
4 libsystem_c.dylib 0x319a529f abort + 94
5 libc++abi.dylib 0x34fb1f6b abort_message + 46
6 libc++abi.dylib 0x34faf34d _ZL17default_terminatev + 24
7 libobjc.A.dylib 0x358e536f _objc_terminate + 170
8 libc++abi.dylib 0x34faf3c5 _ZL19safe_handler_callerPFvvE + 76
9 libc++abi.dylib 0x34faf451 _ZdlPv + 0
10 libc++abi.dylib 0x34fb079f __cxa_throw + 122
11 RedLaserSample 0x000404a9 _ZN5zxing6qrcode19FinderPatternFinder18selectBestPatternsEv + 172
12 RedLaserSample 0x000415e9 _ZN5zxing6qrcode19FinderPatternFinder4findERKNS_11DecodeHintsE + 512
13 RedLaserSample 0x0003a7f7 _ZN5zxing6qrcode8Detector6detectERKNS_11DecodeHintsE + 366
14 RedLaserSample 0x00046b97 _ZN5zxing6qrcode12QRCodeReader6decodeENS_3RefINS_12BinaryBitmapEEENS_11DecodeHintsE + 130
15 RedLaserSample 0x0004ec35 _ZN5zxing6Reader6decodeENS_3RefINS_12BinaryBitmapEEE + 240
16 RedLaserSample 0x00058455 -[FormatReader decode:] + 116
17 RedLaserSample 0x00013835 -[ZXingDecoder findCodesInBitmap:bytesPerRow:width:height:] + 656
18 RedLaserSample 0x0005f6af -[BarcodePhotoEngine zxingFindBarcodesInPixmap:] + 222
19 RedLaserSample 0x00055f25 __38-[BarcodeEngine findBarcodesInPixMap:]_block_invoke_059 + 76
20 libdispatch.dylib 0x34635c59 _dispatch_call_block_and_release + 12
21 libdispatch.dylib 0x34637d0f _dispatch_queue_drain + 274
22 libdispatch.dylib 0x34637b75 _dispatch_queue_invoke$VARIANT$mp + 40
23 libdispatch.dylib 0x346387e7 _dispatch_worker_thread2 + 210
24 libsystem_c.dylib 0x31967dfb _pthread_wqthread + 294
25 libsystem_c.dylib 0x31967cd0 start_wqthread + 8
=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================
Running the very similar RedLaser Xcode sample project (i.e. no MonoTouch involvement, all objective-c) works fine.
Also, if it is of any significance, disabling all barcode scan types allows the BarcodePickerController to load up and display the camera view. Obviously it never detects a barcode though.
The crash you mention has been fixed in the bindings now.
It was related to QR's usage of C++ exceptions and incorrect linking arguments.