EmpireKicking

HTML Logic is our name for the additional tags available in IPS4's templates that allow runtime logic to be executed. It comprises if/then/else statements as well as loops and more.
Since HTML Logic has access to all of the underlying PHP framework in IPS4, it's very powerful and a lot can be achieved with it. One common use is to limit certain content within a template to particular member groups. Let's see how that might be done.
 
Showing or hiding content only to guests
We'll first look at a simpler idea: showing or hiding content specifically to guests (i.e. anyone who isn't logged in). Within IPS4, the \IPS\Member::loggedIn() object contains information about the current user. Guests always have a member_id of NULL (i.e. no value), so we can simply check that value in our logic tag:
{{if \IPS\Member::loggedIn()->member_id === NULL}} This content *only* shows to guests, since they have a NULL member_id. {{endif}} {{if \IPS\Member::loggedIn()->member_id}} This content *only* shows to logged-in users since their member_id is a number, which will equal true. {{endif}}  
Showing content only to specific groups
Let's go a bit further and this time show content to specific (primary) member groups. First, you need to get the IDs for the group(s) you want to deal with. You can find this by editing the group in the AdminCP, and making a note of the id parameter in the URL. On my installation, the Administrator group is ID 4 so we'll use that in our example.
Once again, we're using the \IPS\Member::loggedIn() object, but this time we're using the member_group_id property.
{{if \IPS\Member::loggedIn()->member_group_id === 4}} This content only shows to members in the "Administrators" group (ID 4 in our example) {{endif}}  
Working with multiple groups at once
Following the code above, you could simply repeat the check against \IPS\Member::loggedIn()->member_group_id several times, for each ID you want to allow. However, since our templates allow arbitrary PHP expressions to be used, there's a neater way: use an array of member group IDs you want to allow, and check against that using PHP's in_array function. Here's an example where we only show content to group IDs 2, 4 and 6:
{{if in_array( \IPS\Member::loggedIn()->member_group_id, array( 2, 4, 6 ) )}} This content only shows to members in groups with the ID 2, 4 or 6. {{endif}}  
Have a request for a theme tip? Let us know in the comments and we'll try and help out in a future tip! 

Activity Streams were first introduced in version 4.1 and have been very well received by people who enjoy all the flexibility they create in filtering and sorting content in a community for easy discovery of what is being posted.
As with any new feature, we received a lot of feedback and have had time to take that in and make improvements to mature the Activity Streams with key changes in 4.1.9 being interface, performance, and bug fixes in the system.
One recurring theme we heard were people saying "the new Activity Streams cannot do..." when actually they could do it but the options were not obvious. We used to have the options in a large drop down box that users could edit and then save to update their Stream. This meant that options were not clearly visible and therefore people did not even know all the powerful settings available to them. So in 4.1.9 we have moved those options into a new dynamic filter bar.

With the new filter bar you see all your options available right there. We also changed the interface so Streams instantly update when you make a change. You no longer have to click save and update, wait for interface to collapse, and so on. Now your changes instantly update your Stream.
When you do change your Stream settings a save button appears prompting you to save your new selection. You can choose to save if you like the new options or not if it is just a temporary change you made. If you edit filters on a stream you do not own then it will prompt you to save your options as a new stream.
 
We hope you enjoy this more dynamic approach to Activity Streams.

Several clients have asked how we placed the Twitter feed block on the sidebar of our News page. It's really quite easy and a great demo of how you can place custom HTML in our system. Here is how it was done:
Get the embed code from Twitter Create a custom HTML block in our Pages app Drag and drop that block into the sidebar That really is it! Here is a video walkthrough:
This is a basic example of a custom HTML block that you can use in so many different ways. You could create a "call to action" the only shows to Guests to get them to register. You might also create text that only displays to your staff with quick links to areas they need.
Here we demo dragging the block into the sidebar. You can also put blocks right in theme templates and use them in many more ways. That will be covered in future theme tips.