var clazz: NSObject.Type = TestObject.self
var instance : NSObject = clazz()
if let testObject = instance as? TestObject {
println("yes!")
}
I haven't found a way to create AnyClass from a String (without using Obj-C). I think they don't want you to do that because it basically breaks the type system.
UPDATE: Starting with beta 6 NSStringFromClass will return your bundle name plus class name separated by a dot. So it will be something like MyApp.MyClass
Swift classes will have a constructed internal name that is build up of the following parts:
It will start with _TtC,
followed by a number that is the length of your application name,
followed by your application name,
folowed by a number that is the length of your class name,
followed by your class name.
So your class name will be something like _TtC5MyApp7MyClass
You can get this name as a string by executing:
var classString = NSStringFromClass(self.dynamicType)
Update In Swift 3 this has changed to:
var classString = NSStringFromClass(type(of: self))
Using that string, you can create an instance of your Swift class by executing:
var anyobjectype : AnyObject.Type = NSClassFromString(classString)
var nsobjectype : NSObject.Type = anyobjectype as NSObject.Type
var rec: AnyObject = nsobjectype()
Note that Swift classes are namespaced now so instead of "MyViewController" it'd be "AppName.MyViewController"
Deprecated since XCode6-beta 6/7
Solution developed using XCode6-beta 3
Thanks to the answer of Edwin Vermeer I was able to build something to instantiate Swift classes into an Obj-C class by doing this:
// swift file
// extend the NSObject class
extension NSObject {
// create a static method to get a swift class for a string name
class func swiftClassFromString(className: String) -> AnyClass! {
// get the project name
if var appName: String? = NSBundle.mainBundle().objectForInfoDictionaryKey("CFBundleName") as String? {
// generate the full name of your class (take a look into your "YourProject-swift.h" file)
let classStringName = "_TtC\(appName!.utf16count)\(appName)\(countElements(className))\(className)"
// return the class!
return NSClassFromString(classStringName)
}
return nil;
}
}
// obj-c file
#import "YourProject-Swift.h"
- (void)aMethod {
Class class = NSClassFromString(key);
if (!class)
class = [NSObject swiftClassFromString:(key)];
// do something with the class
}
Apparently, it is not possible (anymore) to instantiate an object in Swift when the name of the class is only known at runtime. An Objective-C wrapper is possible for subclasses of NSObject.
At least you can instantiate an object of the same class as another object given at runtime without an Objective-C wrapper (using xCode Version 6.2 - 6C107a):
class Test : NSObject {}
var test1 = Test()
var test2 = test1.dynamicType.alloc()
In Swift 2.0 (tested in the beta2 of Xcode 7) it works like this:
protocol Init {
init()
}
var type = NSClassFromString(className) as? Init.Type
let obj = type!.init()
For sure the type coming from NSClassFromString have to implement this init protocol.
I expect it is clear, className is a String containing the Obj-C runtime name of the class which is by default NOT just "Foo", but this discussion is IMHO not the major topic of your question.
You need this protocol because be default all Swift classes don't implement an init method.
func newForName<T:NSObject>(p:String) -> T? {
var result:T? = nil
if let k:AnyClass = NSClassFromString(p) {
result = (k as! T).dynamicType.init()
}
return result
}
...where "p" stands for "packaged" – a distinct issue.
But the critical cast from AnyClass to T currently causes a compiler crash, so in the meantime one must bust initialization of k into a separate closure, which compiles fine.
var className = "YourAppName.TestViewController"
let aClass = NSClassFromString(className) as! UIViewController.Type
let viewController = aClass.init()
I use different targets, and in this case the swift class is not found. You should replace CFBundleName with CFBundleExecutable. I also fixed the warnings:
let vcName = "HomeTableViewController"
let ns = NSBundle.mainBundle().infoDictionary!["CFBundleExecutable"] as! String
// Convert string to class
let anyobjecType: AnyObject.Type = NSClassFromString(ns + "." + vcName)!
if anyobjecType is UIViewController.Type {
// vc is instance
let vc = (anyobjecType as! UIViewController.Type).init()
print(vc)
}
Also in Swift 2.0 (possibly before?) You can access the type directly with the dynamicType property
i.e.
class User {
required init() { // class must have an explicit required init()
}
var name: String = ""
}
let aUser = User()
aUser.name = "Tom"
print(aUser)
let bUser = aUser.dynamicType.init()
print(bUser)
Output
aUser: User = {
name = "Tom"
}
bUser: User = {
name = ""
}
