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Xojo Programming Blog Posts

Easily Sorting Arrays of Classes

Published March 9, 2016 by Paul Lefebvre

Sometimes you’re going to need a data structure that is an array of classes and you’re going to want to sort them. The standard array Sort method can only sort simple types (Text, Integer, etc), so what do you do?

The traditional technique has been to use SortWith. You create a separate array of a simple type, populate it and then sort the temporary array using SortWith to sort the class array.

But there is an even slicker way to sort that was added in 2015 Release 3. You can now create your own custom comparison method and use that to sort the class. This custom method returns 0 if the values to compare are equal, a positive if the first value is greater than the second, and a negative value if the first value is less than the second.

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Raspberry Pi 3 Announced!

Published March 8, 2016 by Paul Lefebvre

On Monday February 29th, the Raspberry Pi Foundation announced the new Raspberry Pi 3. This updated Pi has some significant improvements over the Pi 2, including:

  • A 1.2GHz 64-bit quad-core ARM Cortex-A53 CPU (~10x the performance of Raspberry Pi 1)
  • Integrated 802.11n wireless LAN and Bluetooth 4.1
  • Complete compatibility with Raspberry Pi 1 and 2

That last bullet point is notable because it means that Xojo is also fully compatible with the new Raspberry Pi 3!

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Sorry, You’ve Run Out of Memory

Published March 4, 2016 by Geoff Perlman

Most of us build apps without thinking too much about how much memory the app will need. Sure sometimes you end up creating an app that is a real memory buster but that’s unusual. With virtual memory, gone are the days when your app would just run out of memory and crash, or are they?

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How to Recursively Delete a Folder

Published March 2, 2016 by William Yu

While Xojo doesn’t currently provide a direct way of recursively deleting a folder, there are various options that will allow you to do this:

1. Recursively iterate through all the folders, deleting each one. You can read about that at our Developer Site, this is the best cross-platform way.
2. Use the Shell to recursively delete a folder (i.e. “del /s” on Windows, or “rm -rf” on OS X and Linux)

Windows specific ways:
3. SHFileOperation (an older API)
4. IFileOperation (the more modern API that Windows recommends over option #3)

I’ve decided to look at option #4, since this allows more customized options, like the ability to show a progress dialog. However, it is also the slightly more complicated option since it deals with COM & Delegates. The example illustrates this:

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If Smartphone Encryption Is A Red Herring, How Do We Track The Bad Guys?

Published February 4, 2016 by Geoff Perlman

In the blog post Smartphone Encryption is a Red Herring, I pointed out the folly of requiring an encryption back door for the Good Guys to use. So the question arises- “What can be done? If we don’t want a global encryption back door that can be used by anyone, can we still track the Bad Guys?”

The answer is yes. There are plenty of options that don’t require a global back door. I’m not passing judgment on whether these are inherently good or bad options, just that they are available when there is a reason to track a Bad Guy.

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Smartphone Encryption is a Red Herring

Published January 27, 2016 by Geoff Perlman

EnigmaMachine.pngAs the Founder and CEO of a software company that makes a development tool for mobile platforms, as well as for desktop and web, I have a lot of experience with encryption. The current controversy over encryption is really important to me. During World War II, the Germans created a way of sending encrypted messages to commanders in the field. The device came to be known as an Engima machine. It looked like a typewriter but had an encryption key that changed a message into unreadable noise. That message could only be decoded if you knew the key used to encrypt it. The Allies worked very hard to get their hands on one of these devices so they could learn how it works and be able to decrypt the messages and know what the German military plans. Ultimately the Allies figured it out and it helped them win the war. If this has peaked your curiosity, check out the movie U-571 (a fictional account of the effort to obtain an Enigma machine) and The Imitation Game about the team that figured out the encryption key.

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