core-bundle/src/Resources/contao/widgets/CheckBoxWizard.php
protected function generateCheckbox($arrOption, $i, $strButtons)
	{
		return sprintf('<span><input type="checkbox" name="%s" id="opt_%s" class="tl_checkbox" value="%s"%s%s onfocus="Backend.getScrollOffset()"> %s<label for="opt_%s">%s</label></span>',
						$this->strName . ($this->multiple ? '[]' : ''),
						$this->strId.'_'.$i,
						($this->multiple ? StringUtil::specialchars($arrOption['value']) : 1),
						(((\is_array($this->varValue) && \in_array($arrOption['value'], $this->varValue)) || $this->varValue == $arrOption['value']) ? ' checked="checked"' : ''),
						$this->getAttributes(),
						$strButtons,
						$this->strId.'_'.$i,
						$arrOption['label']);
	}
protected function generateCheckbox($arrOption, $i, $strButtons)
	{
		return sprintf('<span><input type="checkbox" name="%s" id="opt_%s" class="tl_checkbox" value="%s"%s%s onfocus="Backend.getScrollOffset()"> %s<label for="opt_%s">%s</label></span>',
						$this->strName . ($this->multiple ? '[]' : ''),
						$this->strId.'_'.$i,
						($this->multiple ? StringUtil::specialchars($arrOption['value']) : 1),
						(((\is_array($this->varValue) && \in_array($arrOption['value'], $this->varValue)) || $this->varValue == $arrOption['value']) ? ' checked="checked"' : ''),
						$this->getAttributes(),
						$strButtons,
						$this->strId.'_'.$i,
						$arrOption['label']);
	}
Generate a checkbox and return it as string

@param array   $arrOption
@param integer $i
@param string  $strButtons

@return string