I have a UITableView which is populated by text and images from a JSON file. The TableView Cell is currently sizing correctly for "posts" that do not contain many
The approach I recommend is to set the text of an actual label and get the required height by calling sizeToFit. For this to work, you've got to set the label's numberOfLines property to 0 and set the desired maximum width.
When using this technique with table views, you can use the prototype cell method discussed here to calculate height using an actual cell.