Dave – Page 2 – On The Fence Development

Book Review: Mastering Xamarin.Forms

It may sound odd but from time to time I get approached to review a book which is either due to be or has just been published.

I say odd because I’m just a regular developer – not a podcasting rockstar (or even a blogging one). Why would my option be worth a free copy of a book?

Maybe it’s because I’m just a regular developer – just like most of us.

Some of these I let pass me by, especially if I have no real interest in the content, i.e. a technology that I am not using and have no plans to use – F# for example. I frequently say that ‘you have to pick your fights when it comes to technology – you can’t win them all’.

So, when Packt asked if I would review this book it made me wonder:

“How much of a master can I be after reading a book that’s ‘only’ 200 pages?”.

I’m certainly not belittling the authors efforts, but I have a Microsoft Press book ‘Creating Mobile Apps with Xamarin.Forms‘ which is more than twice that length and that doesn’t claim to be able to make me a ‘Master’.

Getting Started with Visual Studio 2019 Android Navigation Drawer template

So, I’ve had an idea for another privacy-focused application, this time aimed at mobile devices – Android in particular (I know that Apple are a little touchy about encryption apps – maybe I’ll venture into iOS at a later date).

Notwithstanding my desire to keep my skills up to date I knew that the project I have in mind would require a lot of platform specific logic. While Xamarin Forms can handle this I prefer to take the hit, roll my sleeves up and I opted for a native Android project instead – and that’s where the trouble/fun started.

If you go through the ‘New Project’ process below you will end up with an application which will look something like the one above;

Yep -just what I needed, an application with a slide out menu. Now all I need to do is to replace the default options with my own and then open the appropriate views when they are clicked – what could be easier?

IR35 – Living with a Broken Promise

Well I guess it’s old news now, although it was quite foreseeable, but despite a pre-election promise the Conservatives have reneged on their commitment to review the IR35 legislation. Instead they will review the process for rolling the changes into the private sector – not the same thing at all.

Instead of me going over old ground, take a look at my previous IR35 post which was published prior to the election (and it’s broken promises).

In the weeks that have followed Twitter has been ablaze with tweets tagged with #IR35 – many are mine. There is a lot of anger out there and our worst fears, that end clients would take the ‘easy option’ and just stop using contractors altogether has come to pass (despite HMRC saying it wouldn’t).

Take a look at the OffPayroll.org.uk site and you’ll see the extent of the problem that is unfolding.

Unit Testing with the Xamarin.Forms MessagingCenter

While we all know that Test Driven Development (TDD) is a good idea, in practice it’s not always viable. It could be a time constraint, a resource issue or the project just doesn’t warrant it.

While TDD may sometimes be an option, unit tests themselves should really be considered to be a must. They will save you a lot of time in the long run and while they may not prevent you from going grey, ask me how I know, they will reduce your stress levels when bugs raise their ugly heads.

So, whether you write your tests before you write the code or vice-versa, if you are developing production code you really should write tests to cover it.

Now, one of the requirements for unit testing is the ability to mock out a components dependencies so that you are only testing the component itself.

Normally you would use the Dependancy Injection pattern to help develop loosely coupled systems but Xamarin.Forms has a few components which can be a fly in the ointment – one of these is the MessagingCenter.

IR35 2020 – Thoughts from the Coal Face

I’ve been contracting for over eight years now and in that time I’ve been careful to ensure that, to the best of my abilites, I operate in a manner that places me outside of the IR35 legislation. That is, to provide a service to my clients and not to be seen as an employee.

Currently it is my responsibility to determine the employment status of a role with regards IR35. I do this by having contracts independantly reviewed to ensure that they comply with the legislation and take steps to ensure that the actual working conditions are in accordance with service provision rather than employment.

If I get it wrong then it is down to me to justify my determination, in court if need be, and pay any unpaid taxes should I be unable to do so.

However, in April 2020 that determination could largely be taken out of my hands and placed in those of the fee payer, e.g. the client if I’ve been engaged directly or otherwise a recruitment agency that have facilited the engagement.

HMRC have decided to make this change stating their belief that most contractors are incorrectly self-declaring themselves as being outside of IR35 and avoiding paying the correct level of tax.

They have not been able to substantiate these claims, despite repeated calls to do so – but that’s not the reason for this post.

AppSettings in Xamarin.Forms

If you have used ASP.NET in recent years you will probably be familiar with the appSettings.jsonfile and it’s associated, build-specific transformations, e.g. appSettings.development.json and appSettings.release.json.

Essentially these allow developers to define multiple configuration settings which will be swapped out based on the build configuration in play. Common settings are stored in the main appSettings.json file while, for instance, API Endpoint Urls for development and production deployments are stored in the development and release files.

At compile-time any values specified in the deployment version of the file overwrite those in the common version.

Simple – works well and we use it all the time without thinking about it. But what about Xamarin.Forms – it doesn’t have such a mechanism out of the box so how do we achieve this and prevent accidentally publishing an app to the App/Play Stores which are pointing to your development/staging servers?

Roll my own DDNS? Why Not.!

Update: Well, there’s certainly more to Dynamic DNS than meets the eye – who knew.
Investigations led to the decision that I should put my hand in my pocket and spend my time better elsewhere.
Not that I opted for the overpriced offering from Oracle, signing up with NoIp instead.

Like many devs I have been known to host websites and services behind my home broadband router and therefore needed a Dynamic DNS resolver service of some description. But in my recent moves to limit my reliance on third-party services – including those provided by Google – I wanted to see what would be involved in creating my own service.

Why would I want to roll by own?

Over the last few years I’ve moved my hosted websites outside of my home network and onto services offered by Digital Ocean so I was only really using my DDNS provider for a single resource – my Synology NAS.

Now, in the past I’ve used DynDNS (an Oracle product) and while I’ve had no issues with the service it’s not what you could call cheap – currently starting at $55 a year. When a previous renewal came through, and after reviewing what I was using it for, I decided to let it expire and do without the access to the NAS from outside my network.

Updating an end of life application

A while ago I posted that the FillLPG for Android application was, in a word, Dead! But in few days time users will notice a new version, 2.0.28.5, hitting the Play Store as well as in-app notifications to update – so what gives?

Have I changed my mind about withdrawing support for this app – no, I haven’t. Essentially my hand has been forced by Google’s recent decision to deprecate some of the functionality I was using to fetch nearby places as part of the ‘Add New Station’ wizard as well as requiring 64 bit support – the latter being little more than a checkbox and nothing that most users will ever notice.

Removal of the Places Picker

Prior to the update, when adding a new station a user could specify the location in one of two ways;

Select from a list of locations provided by the Google Places API and flagged as ‘Gas Stations’
Open a ‘Place Picker’ in the form of a map and drop a pin on the desired location

It is the second option which is now going away – and there is nothing I can do about it. Google are pulling it and that’s that.

Getting to grips with OzCode

When I was at NDC London in January I watched a demonstration of the OzCode extension for Visual Studio. Not only was it well presented but it highlighted some of the pinch points we all have to tolerate while debugging.

In return for a scan of my conference pass, i.e. my contact details, I received a whopping 35% discount off a licence and without completing the 30 day trial I was so impressed that I pulled out my wallet (actually the company wallet!).

While I don’t use all of the features every day there are a few that I use all the time – the first one is called ‘Reveal‘.

Consider the following situation:

But I already knew this was a list of view models!

At this breakpoint I’m looking at collection of View Models – but I knew that already what value am I getting from this window? There are over 600 records here – do I have to expand each one to find what I’m looking for? What if one has a null value that is causing my problem – how will I find it?

Hey Dude – where’s my online tool?

Over the past 18 months I’ve been posting details of various online tools that I’ve encountered – but not this month I’m afraid.

Why? Well, frankly I’ve run out! I’ve got nothing!

I’ve been hard at work but haven’t actually found the need for an online tool that I haven’t used before.

Now that’s not to say that there aren’t any tools out there – it’s just that I didn’t need them, not this month anyway.
Next month may be different but I think it’s probably best to drop the ‘of the month’ banner and just categorise them as ‘Online Tool’

If you know of a tool that I’ve not featured and think I, as a .NET / Xamarin developer may find useful then feel free to use the contact page to point me in it’s direction.

NDC London – A Little Review

So, the last developers conference (if you could call it that) I went to was way back in 2001 when we had WAP phones and if you had a Pentium 4 computer you were some super-techno hacker.

Well, time have changed somewhat, we now have smart phones with more memory than we had hard drive space back then and I’m writing this post on a workstation with 8 cores and 32GB RAM (and this isn’t even the cutting edge). Add to that the cloud, driverless cars and social networks with billions of users (for better or worse) and we have come a hell of a long way.

Well, I decided to bite the bullet and shell out for a super early-bird ticket and get myself up to London for a few days to Geek-Out.

Online Tool of the Month – converter.telerik.com

Telerik shouldn’t be a new name to you but if it is then I suggest you head on over to their main site, https://www.telerik.com, and have a look.

This post relates to there Code Converter utility which I found a need for recently while maintaining a clients VB.NET application.

Although I used to develop mainly in VB.NET I am now predominantly working in C# and as anyone who has used both languages will tell you, flipping between one and the other is not exactly painless.

The Scourge of Email Click-Bait

We all get some SPAM in our Inboxes – despite the best efforts of our email hosts, be they Google or otherwise. But another type of message is starting to gain traction and I receive a number of these a week now – normally from recruiters is has to be said – and they are akin to the Click-Bait links you see all over the web (you know, the ones that normally end with ‘you’ll never guess what happens next’).

So, what am I talking about? Well, from this mornings Inbox we have ‘Exhibit 1’;

I’ve blurred the sender (although as I type I don’t really know why) but the subject line starts ‘Re:’ which would indicate that this is a reply to an email that I’ve sent – standard email client functionality. But I’ve never emailed (or even heard of) the sender or their company.

It’s just a rouse to get me to click on the message and read what they have to say – because the premise is that we have done business in the past.

Online Tool of the Month – base64-image.de

I recently had a need to create HTML email templates for a project which needed to include a couple of images, e.g. the company logo and feature image. I have of course done this in the past and just linked to the required assets on the hosting website – but this time is was different.

This time the website was potentially not accessible from outside of the local intranet and the requirement was to embed the images directly into the message.

One way to do this is to encode the images to a base64 string and use the resulting text, with a ‘data:image/jpeg;base64,‘ prefix in the src attribute of the image tag – something like this;

<img src="data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD/4QBoRXh....." />

Now all I needed to do was encode the images.