Self Sizing Table View Cells In Interface Builder

Self-sizing table view cells have been around a long time but are still a regular source of confusion. Interface Builder added to the confusion by not automatically sizing the cells in the canvas. That’s finally fixed in Xcode 11!

What’s The Problem?

To recap, a “self-sizing” table view cell should adjust its height to fit the content of the cell at its natural height. To create one follow these rules when laying out the cell:

Doing this in Interface Builder should be straightforward. The table view row height and estimated row height both default to “Automatic”:

Table view row and estimated row height default to Automatic

The prototype cell in Interface Builder doesn’t give you a lot of room to work with. I usually find it best to drag the bottom of the cell down to make some space. Here I’ve made it 100 points high:

Prototype cell

I’ve added a text view with a several lines of placeholder text. The text view has scrolling disabled and is using the .body text style. I added four constraints to pin it to the margins of the content view:

Cell layout

At this point we have a valid layout that is self-sizing when I run it but Interface Builder is none the wiser. It continues to show the cell as being 100 points high truncating most of the text view.

You can see the fixed size the cell takes in the canvas if you select the cell (not the table view) and look in the size inspector. This is what Xcode 10 would show:

Xcode 10 custom cell row height

Note that changing this row height only changes the height of the cell in Interface Builder - it doesn’t change the row height at runtime. If you unclick the “Custom” checkbox the row height goes back to the default:

Xcode 10 default cell row height

Either way, Xcode 10 never shows the table view cell at the correct size for the placeholder content:

Xcode 10 table view cell with no self-sizing

Better Late Than Never…

Here’s the good news buried in the Xcode 11 release notes:

Cells in a UITableView can now self size with Auto Layout constrained views in the canvas. To opt into the behavior for existing table views, enable “Automatic” for the table view estimated item size, and “Automatic” for cell’s height in the Size inspector. (35735970)

Assuming you have switched to Xcode 11, this is how the size inspector looks for the table view cell:

Xcode 11 cell size inspector

Note the “Automatic” checkbox. If you select it Interface Builder wakes up and realizes you have created a self-sizing cell (you can just about read the actual row height of 346.5 points):

Xcode 11 cell size inspector - Automatic selected

The table view cell in the canvas is finally self-sizing:

Self-sized cell in canvas

If you change the text style of the text view the cell resizes in the canvas to take into account the new content size:

Self-sized cell in canvas with smaller text

Note that anytime you manually change the row height of the cell in the canvas it disables the “Automatic” setting in the size inspector.

Why Now?

I’ve no idea why the Xcode engineers suddenly decided to fix this in Xcode 11. It’s not the only example of some dusty corners of Interface Builder getting some polish. See also:

It would appear that not everybody is working on SwiftUI yet. Truly a case of better late than never…

Read More

If you’re still struggling with Auto Layout and self-sizing table view cells you might like my book:

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