Swift Nifty TableViewCell Trick

Published Oct 30, 2017Last updated Apr 28, 2018

Like every Swift developer out there I grew to love TableViewCells and Protocol Oriented Programming. Good because today’s is about a cool trick combining the two !

Let’s see the common way of registering a TableViewCell in Swift_ :_

tableView.register(MyCell.self, forCellReuseIdentifier: “MyCell”)

What bothers me first here is the error-prone string usage, then let’s be honest, 99% of the time , the cell identifier is just the string Cell class name. Maybe some of you see where I’m going with this 😃

As always in Swift, start with a protocol  :

protocol Reusable: class {
  static var reuseIdentifier: String { get }
}

Then make your cell “Reusable” by implementing the protocol like so :

extension MyCell: Reusable {}

And here instead of implementing it, we are going to use Swift’s Protocol Extensions to provide a default value for all reusable objects  !

extension Reusable {
  static var reuseIdentifier: String {
    return String(describing: Self.self)
  }
}

By default reuseIdentifier will be the name of the class !

So you can now write :

tableView.register(MyCell.self, forCellReuseIdentifier: MyCell.reuseIdentifier)

Okay we got rid of the error prone String, but wait we can do better than that can’t we?

Bonus

Surething! Let’s provide a shorter way to register Reusable cells.

Once again, protocols to the rescue!

Here we say, If you are a TableView registering a Reusable TableViewCell, then use cell’s reuseIdentifier by default.

extension UITableView {
  func register<T: UITableViewCell>(_: T.Type) where T: Reusable {
    register(T.self, forCellReuseIdentifier: T.reuseIdentifier)
  }
}

And now you can simply call :

tableView.register(Mycell.self)

It’s as short as we can get I’m afraid 🎉🎉🎉

Wrap-up

Here we used Swift amazing protocol extensions to remove error-prone string identifier in a very common usage of TableViewCells.

We made the code both shorter and clearer while saving us from writing all of our UITableViewCells reuseIdentifiers by hand !

Remember, the best code is the one you don’t have to write 😃


If you liked this trick you will probably love the iOS tools we make @freshos


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Originally published here

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