![]() ![]() There are many different errors but this is the most common error: System.NullReferenceException ![]() I used it in another project where it had to work with a custom protocol to with the host device.Recently when trying to open iOS UI Designer to edit storyboard/xib file, I have encounter some problems. This issue is also reported in Xamarin BugZilla: Problem 1: ViewControler is rendered but with error exclamation mark It’s very good at reading different card types and you can write custom firmware for it in C. The TWN4 has become my favorite RFID reader. The end result was that I ended up with all C# code and it works great. When changes are made to that library, I can view those changes and make the equivalent changes in the C# code. I also took the C# helpers from the LusoVU repository.Īs much as I could do so, I followed the code structure’s of the Java library. I also replaced some integer constants with enumerated types where it made sense to do so. In the original Java (edited) code, we had this final ByteBuffer buf = ByteBuffer. In the CdcAcmSerialPort.Read() method, defined here in C# and here in Java, I needed to add a line to copy the new array back over the original array. ![]() This is logged in Xamarin’s Bugzilla database here and here. Changes made to the ByteBuffer are not reflected in the original byte array. In Java, ByteBuffer.wrap(someBuffer) allows for two-way updating of a Java array with a stream buffer, A bug in Xamarin’s API mapping tool emits code that allocates a new buffer when you call Wrap. There were also a bug in Xamarin’s API access code that mangled the array handling in some Java code. Some changes needed to made because reflection is handled differently in C# than in Java. It took a couple of days, but I was able to port all of the Java code to C#. If you have the source code, you can port the code from Java to C#. You would also have the limitation of not being to debug into that code library. It looked like their project was abandonware and was not using a current version of Mike’s code. While that can work, and work very well, it can also be a bit clunky and you can hit some issues mapping the Java method calls to C#. You can use them directly by creating a C# to Java wrapper and bundling the. ![]() With Xamarin Android, you have basically two ways of consuming Java libraries. It supports many of the common USB serial chipsets. There was enough of a need for serial devices that Mike Waverly wrote a very good library in Java named usb-serial-for-android. Starting in Android 3.1, support was added for USB Host mode to allow access to USB devices from Android apps. Out of the box, Android doesn’t come with a lot of support for serial port devices. That ported library is up on Github under the name UsbSerialForAndroid. I ended taking a very good one from the open source Java community and porting it over to C#. To use that reader, I needed a general purpose serial over USB library. The reader is an Elatec TWN4 RFID reader and it can work as virtual comm port over USB. We have an Android application that needs to use an external RFID reader. A Xamarin port of the usb-serial-for-android libraryīack in January, I ported the excellent usb-serial-for-android library from the Java source code to Xamarin C#. ![]()
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