CODEWITHSUNDEEP
iosswiftgenericsmetaprogrammingmetaclass
Taco
Taco

Reputation: 700

How to convert a string with the name of a class to the class type itself?

In order to store a class name in a log file I converted the description of a class type to a string:

let objectType: NSObject.Type = Object.self
let str = String(describing: objectType)

However, I do not succeed in back conversion of str to a variable of type NSObject.Type to use it in a generic method.

How could I do this?

Upvotes: 11

Views: 8828

Answers (3)

Danny Yassine
Danny Yassine

Reputation: 681

I simply created an extension to use on any object:

extension NSObject {

    // Save Name of Object with this method
    func className() -> String {

        return NSStringFromClass(self.classForCoder)

    }

    // Convert String to object Type
    class func objectFromString(string: String) -> AnyObject? {
        return NSClassFromString(string)
    }

}

The method classForCoder prints out the module name with the class name. Then you must that string in order to convert it back to its respective object type.

Upvotes: 1

pflous
pflous

Reputation: 571

Perhaps something like:

let objectType: NSObject.Type = NSObject.self 

let str = String(objectType) // str = "NSObject"

let aClass = NSClassFromString(str) as! NSObject.Type // aClass = NSObject.Type

Upvotes: 0

Santosh
Santosh

Reputation: 2914

You can get your class back from string, but you need to use your project's module name while getting class name. If you don't use your module name then it will return nil because the class name you have referenced earlier is not fully qualified by the module name. You should change the class name string to represent the fully qualified name of your class: 

let myClassString = String(MyModule.MyViewController.self)
print(myClassString)
let myClass = NSClassFromString("MyModule.\(myClassString)") as! MyViewController.Type
print(myClass)

Upvotes: 6

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