Swift-以编程方式加载情节提要

Question

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // step 1. check the device
    var idiom = UIDevice.currentDevice().userInterfaceIdiom

    // step 2. take a storyboard variable
    var storyBoard:UIStoryboard? = nil

    // step 3. load appropriate storyboard file
    if idiom == UIUserInterfaceIdiom.Phone {
        storyBoard = UIStoryboard(name: "Main", bundle: nil)
    } else {
        storyBoard = UIStoryboard(name: "Main_iPad", bundle: nil)
    }

    // step 4. un-box storyboard to sb variable
    if let sb = storyBoard {

        // step 5. create new window
        window = UIWindow(frame: UIScreen.mainScreen().bounds)

        // step 6. generates error :( 'Cannot assign to the result of this expression'
        self.window?.rootViewController?.storyboard = sb

        // step 7. make key window & visible
        window?.makeKeyAndVisible()
    }
    return true
}

I get error on step-6 ! As I'm new to swift, I'm finding it bit difficult what to code here.

Answer 1

The storyboard is just an XML file holding the information about your view controllers. You should use it to instantiate view controllers (or maybe other controllers such as tab bar controllers or navigation controllers) to set as your application window's root view controller.

window.rootViewController = sb.instantiateInitialViewController() as MyWhateverController