TYPO3 v8
Updated the answer for TYPO3 v8. This is quoted from Claus answer below:
Updating this information with current situation:
On TYPO3v8 and later, the following syntax is supported which fits
perfectly with your use case:
<f:if condition="{logoIterator.isFirst}">
<f:then>First</f:then>
<f:else if="{logoIterator.cycle % 4}">n4th</f:else>
<f:else if="{logoIterator.cycle % 8}">n8th</f:else>
<f:else>Not first, not n4th, not n8th - fallback/normal</f:else>
</f:if>
In addition there is support for syntax like this:
<f:if condition="{logoIterator.isFirst} || {logoIterator.cycle} % 4">
Is first or n4th
</f:if>
Which can be more appropriate for some cases (in particular when using
a condition in inline syntax where you can't expand to tag mode in
order to gain access to the f:else with the new if argument).
TYPO3 6.2 LTS and 7 LTS
For more complex if-Conditions (like several or/and combinations) you can add your own ViewHelper in your_extension/Classes/ViewHelpers/. You just have to extend Fluids AbstractConditionViewHelper. The simple if-ViewHelper that shipps with Fluid looks like this:
class IfViewHelper extends \TYPO3\CMS\Fluid\Core\ViewHelper\AbstractConditionViewHelper {
/**
* renders <f:then> child if $condition is true, otherwise renders <f:else> child.
*
* @param boolean $condition View helper condition
* @return string the rendered string
* @api
*/
public function render($condition) {
if ($condition) {
return $this->renderThenChild();
} else {
return $this->renderElseChild();
}
}
}
All you have to do in your own ViewHelper is to add more parameter than $condition, like $or, $and, $not etc. Then you just write your if-Conditions in php and render either the then or else child. For your Example, you can go with something like this:
class ExtendedIfViewHelper extends \TYPO3\CMS\Fluid\Core\ViewHelper\AbstractConditionViewHelper {
/**
* renders <f:then> child if $condition or $or is true, otherwise renders <f:else> child.
*
* @param boolean $condition View helper condition
* @param boolean $or View helper condition
* @return string the rendered string
*/
public function render($condition, $or) {
if ($condition || $or) {
return $this->renderThenChild();
} else {
return $this->renderElseChild();
}
}
}
The File would be in your_extension/Classes/ViewHelpers/ExtendedIfViewHelper.php Then you have to add your namespace in the Fluid-Template like this (which enables all your self-written ViewHelpers from your_extension/Classes/ViewHelpers/ in the template:
{namespace vh=Vendor\YourExtension\ViewHelpers}
and call it in your template like this:
<vh:extendedIf condition="{logoIterator.isFirst}" or="{logoIterator.cycle} % 4">
<f:then>Do something</f:then>
<f:else>Do something else</f:else>
</vh:extendedIf>
Edit: updated.
<f:if condition="{rank} % 2">Will be shown if rank % 2 != 0.</f:if>– Poetry