Xamarin - Working with threads

Mobile devices are optimised to run complex tasks on multiple threads. Running any form of complex task on the UI thread (the main thread) will cause the UI of your application to hang (or at least seem to anyway) until the operation is complete. The fix is to run the task on another thread and return a result back to the UI thread.

So if you find your aplication seemingly becoming unresponsive whilst running a complex or long running task like fetching a user profile from the web, then remember, run it in another thread and have a think about what other opperations can be pushed to another thread. The performance improvement is worthwhile too, since most new phones hitting the market have at least four CPU cores (some even come with eight!) the phone is more than capable of running multiple tasks at once. Your users will be thanking you too.

So running something on another thread is simple enough, simply make a new task...

Task.Run(async () =>
{
    // Run code here
})

Now if you add your code to a new task, it'll run on another thread. Just be aware that if you want to effect anything in the UI from this thread, the system will prevent this and throw an exception. To get around this, you'll need to add another small piece of code that will execute the UI action on the UI thread, here's how:

Device.BeginInvokeOnMainThread(() =>
{
    // UI interaction goes here
});

That's pretty much it. Almost anything can be run inside another thread. Here's an example of everything together so c=you can see how it's constructed:

Task.Run(async () =>
{
    // Run code here

    Device.BeginInvokeOnMainThread(() =>
    {
        // UI interaction goes here
    });
})

Good luck!


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Tags: Xamarin,C#,Multi Tasking

Luke Alderton

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