Widget front-end fails to echo as expected from checkbox

Question

Context: This is my first widget and I am following along with an online tutorial. I am expecting the front-end of the widget to echo some content upon checking a check-box in the back-end form, but rather I am not seeing any content displayed.

Reference Material:

• I have attempted to follow along with these two-part tutorials http://www.wpexplorer.com/create-widget-plugin-wordpress/ and http://www.wpexplorer.com/how-to-create-a-widget-plugin-for-wordpress-part-2/ .

• My complete widget file is located here http://pastebin.com/nVTzxiTQ

screenshots:

Back-end looks like this after saving

Front-end looks like this after saving

Question: Why isn't the act of checking the check-box in the back-end UI resulting in the rendering of the string 'Checkbox is checked' on the front-end, as I expect it to?

Answer 1

on line 49 it seems you have hardcoded in the checkbox value it should actually look like this, it was always going to be true even if it did work as intended:

<input id="<?php echo $this->get_field_id('checkbox'); ?>" name="<?php echo $this->get_field_name('checkbox'); ?>" type="checkbox" value="<?php echo $checkbox; ?>" <?php checked( '1', $checkbox ); ?> />

also after line 81 add this in:

$checkbox = $instance['checkbox'];

Line numbers are based on what's in pastebin