How to create an instance of a class from a String in Swift

Question

I have tried creating an instance of a class using a string in numerous ways with none of them working in Swift 3.

Below are pre-Swift 3 sol

Answer 1

If you project contains space you should replace space with '_'

Something like this

let namespace = (Bundle.main.infoDictionary!["CFBundleExecutable"] as! String).replacingOccurrences(of: " ", with: "_")
let cls = NSClassFromString("\(namespace).\(className)")! as! AnyClass

Answer 2

Apple provides a way to achieve this without having to use NSClassFromString.

Bundle.main.classNamed("MyClassName")

https://developer.apple.com/documentation/foundation/bundle/1407299-classnamed

Answer 3

Typed Extension

You can have a typed class from a string like:

let loadedClass = try! Bundle.main.class(ofType: MyClass.self)

using this simple extension:

extension Bundle {
    func `class`<T: AnyObject>(ofType type: T.Type, named name: String? = nil) throws -> T.Type {
        let name = name ?? String(reflecting: type.self)

        guard name.components(separatedBy: ".").count > 1 else { throw ClassLoadError.moduleNotFound }
        guard let loadedClass = Bundle.main.classNamed(name) else { throw ClassLoadError.classNotFound }
        guard let castedClass = loadedClass as? T.Type else { throw ClassLoadError.invalidClassType(loaded: name, expected: String(describing: type)) }

        return castedClass
    }
}

extension Bundle {
    enum ClassLoadError: Error {
        case moduleNotFound
        case classNotFound
        case invalidClassType(loaded: String, expected: String)
    }
}

_{Of course you can try catch the error ;)}

Answer 4

You can try this:

func classFromString(_ className: String) -> AnyClass! {

    /// get namespace
    let namespace = Bundle.main.infoDictionary!["CFBundleExecutable"] as! String

    /// get 'anyClass' with classname and namespace 
    let cls: AnyClass = NSClassFromString("\(namespace).\(className)")!

    // return AnyClass!
    return cls
}

use the func like this:

class customClass: UITableView {}   

let myclass = classFromString("customClass") as! UITableView.Type
let instance = myclass.init()