Get class from string and Pass parameters in Swift

Question

I have a method in objective-c which takes string and converting to class and passing some common object to it.

-(UIViewController*)getUIViewController{
 NSString* templateID = @"templateId"; // This value is coming from ba ckend
Class c = NSClassFromString(templateID);
UIViewController* vc = [[c alloc] initWithAppRender:appRenderer];
return vc;
}

Now the same thing converting to swift.

func getUIViewController() -> UIViewController? {
    let templateID = "templateId"
    let className = Bundle.main.infoDictionary!["CFBundleName"] as! String + "." + templateID
    let aClass = NSClassFromString(className) as! UIViewController.Type
    return aClass.init()
}

Here the problem is not able to pass common object which exists in all view controllers. I want to pass apprenderer object like in objective-c.

You would need to extend UIViewController to have an additional convenience init that accepts an appRenderer — Paulw11
– Paulw11, Commented Apr 20, 2018 at 11:32
@Paulw11 Even though i have convenience init. I need to warp the view controller from class object. I want to pass with out wrapping — Sivakrishna Perla
– Sivakrishna Perla, Commented Apr 20, 2018 at 11:36
Instantiating a class from Type can be done with required initializer but as we can not add a required initializer in extension so seems impossible by extending UIViewController. Can you share obj-c code of initWithAppRender where it is defined, It might be helpful to find some solution? — Kamran
– Kamran, Commented Apr 20, 2018 at 11:44

Kamran · Accepted Answer · 2018-04-20 11:59:48Z

1

I would suggest you to create a base class for all your ViewControllers like this,

class BaseViewController: UIViewController {

    private var render: NSObject?

    required init(appRenderer: NSObject?) {
        super.init(nibName: nil, bundle: nil)

        self.render = appRenderer
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

And then you can instantiate from the server returned class name as below,

func getUIViewController() -> UIViewController? {
    let templateID = "templateId"
    let className = Bundle.main.infoDictionary!["CFBundleName"] as! String + "." + templateID
    let aClass = NSClassFromString(className) as! BaseViewController.Type
    let vc = aClass.init(appRenderer: nil)
    return vc
}

answered Apr 20, 2018 at 11:59

Kamran

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1 Comment

Sivakrishna Perla Over a year ago

can u please suggest how to load view from storyboard in this case.

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