First off, you’re using a nib file to load your custom cell into the table. That’s probably going to be more of a headache than it’s worth if you’re new to Swift/Cocoa. I would move everything over to storyboard for the time being. Instead of using a nib file click, go to Storyboard, click on your UITableView and make sure the TableView’s content setting is Dyanamic Prototypes:
Next, click on the prototype cell (the only one in the table view) and set the class to CustomTableViewCell and set its reuse identifier to customCell:
Next, add a label to your prototype cell and link it to the IBOutlet in your CustomTableViewCell class. You don’t need to register your customCell so long as you’ve set the reuse identifier in storyboard. Delete this line:
self.tableView.registerClass(CustomTableViewCell.self, forCellReuseIdentifier: "customCell")
and it should run.