NSStringFromClass in Swift is Here!

Posted on January 14th, 2016

One of the first things I immediately noticed was missing from Swift was the NSStringFromClass replacement. I like to use the class name for my TableViewCell identifiers, and then just NSStringFromClass to dequeue the cells to avoid spelling issues.

In Swift, I would write an ugly extension to do that as seen in this StackOverflow answer:

public extension NSObject{
    public class var nameOfClass: String{
        return NSStringFromClass(self).componentsSeparatedByString(".").last!
    }

    public var nameOfClass: String{
        return NSStringFromClass(self.dynamicType).componentsSeparatedByString(".").last!
    }
}

public extension NSObject{

public class var nameOfClass: String{

return NSStringFromClass(self).componentsSeparatedByString(".").last!

}

public var nameOfClass: String{

return NSStringFromClass(self.dynamicType).componentsSeparatedByString(".").last!

}

Not sure when it happened, but I was extremely to see a more native solution in @aligatr’s blog post!

// This now works!!!
String(MyTableViewCell)

1 2	// This now works!!! String(MyTableViewCell)

I tried it out myself just to be sure and it actually works!!

Custom BlueTableViewCell

// BlueTableViewController
    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        
        // the cell gets dequeued properly!!!
        let cell = tableView.dequeueReusableCellWithIdentifier(String(BlueTableViewCell), forIndexPath: indexPath)

        return cell
    }

// BlueTableViewController

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

// the cell gets dequeued properly!!!

let cell = tableView.dequeueReusableCellWithIdentifier(String(BlueTableViewCell), forIndexPath: indexPath)

return cell

}

Super excited I don’t have to use the extension anymore!

Allan Bto

Hey Natasha,

Great idea! I’m also using it for my UITableViews, I wrote this little extension to help me:


extension UITableView
{

    public func dequeueReusableCell(type: T.Type) -> T
    {
        guard let cell = self.dequeueReusableCellWithIdentifier(String(type)) as? T else {
            fatalError("(String(type)) cell could not be instantiated because it was not found on the tableView")
        }

        return cell
    }

}

extension UITableView

{

public func dequeueReusableCell(type: T.Type) -> T

guard let cell = self.dequeueReusableCellWithIdentifier(String(type)) as? T else {

fatalError("(String(type)) cell could not be instantiated because it was not found on the tableView")

Dima Pilipenko

wow, good.

I have changed also:

https://github.com/dimpiax/FlexibleTableViewController/blob/master/FlexibleTableViewController/CustomUITableViewCell.swift
Nuno

Hoo.. This is really nice. I used a similar approach. Without generics though. Thanks 🙂

Lasha Efremidze

Whats the difference between String(self) and String(reflecting: self)?
Limon

I use it.
extension UICollectionReusableView {
static var reuseIdentifier: String { return "(self)" }
}
IanKay

Nice: I was able to simplify this

https://gist.github.com/IanKeen/4ecbffea1e9d0c1bf1d6
Juan Collas

Under Xcode 7.1, I’ve started using this:

String(self.dynamicType)

or in a protocol,

String(Self)

I found this somewhere in stack overflow, I’m sure.
KenZhang9999

This library does a great help on identifiers of cells, segues, resources. You can use automatically generated constants instead of strings.
https://github.com/mac-cain13/R.swift
fabb

The Swift variant does not include the module name though, while the ObjC variant does. Might lead to name clashes in the very rare case that same-named reusable views from different modules are used within the same collection/table view.
Eduardo Milpax Díaz

This does not work on Swift 3
- Ilya Denisov
  
  Yep, for swift 3
  let className = String(describing: SomeClass.self)