Let's pretend we have an UITableViewController
that on didSelectRowAtSection
loads an instance of a class named i.e.: ClassToInject
and it wants to inject it through a property injection because our ViewControllerToBePushed
has a property of ClassToInject
, that subsequently (because it's an UITabBarViewController
) on the didSet
callback it searches for all its viewControllers
property that conforms to ClassToInjectPresentable
simple as:
protocol ClassToInjectPresentable {
var property: ClassToInject { get set }
}
Until now, i would just do something like this:
func didSelectRowAtIndexPath {
let classToInject = self.loadClassToInjectFor(indexPath)
let tabBarViewController = SomeTabBarViewController()
tabBarViewController.property = classToInject
self.navigationController.push(tabBarViewController, animated: true)
}
And in SomeTabBarViewController
...
class SomeTabBarViewController: ClassToInjectPresentable {
var property: ClassToInject? {
didSet(newValue) {
self.viewControllers.filter{ $0 is ClassToInjectPresentable }.map{ $0 as! ClassToInjectPresentable }.forEach{ $0.property = newValue }
}
}
And everything should be get loaded nice and easy (but it's not). I've read about Swinject
and this might be solved with it. I have seen lots of examples registering things like:
container.register(Animal.self) { _ in Cat(name: "Mimi") }
But I don't know if I can register some property that is loaded in self
:
container.register(ClassToInjectInjector.self) { _ in
self.loadClassToInjectFor(indexPath) }
// And then
container.register(ClassToInjectPresentable.self) { _ in
SomeTabBarViewController() }
.initCompleted { r, p in
let tabBar = p as! SomeTabBarViewController
tabBar.property = r.resolve(ClassToInjectInjector.self)
// And lastly?
self.navigationController.pushViewController(tabBar, animated: true)
}
}
Finally I got the final answer by following the suggestions proposed.
public class Containers {
fileprivate init() { }
}
extension Containers {
static let activityPresentableContainer: Container = {
let container = Container()
container.register(ActivityTabBarController.self) { (r: Resolver, arg1: Activity) in
return ActivityTabBarController(activity: arg1)
}
container.register(ActivityPresentable.self) {
(r: Resolver, arg1: ActivityPresentableTabs, arg2: Activity) in
switch arg1 {
case .summary:
return ActivitySummaryViewController(activity: arg2)
case .detail:
return ActivityDetailPageViewController(activity: arg2)
case .map:
return ActivityMapViewController(activity: arg2)
case .charts:
return ActivityChartsViewController(activity: arg2)
case .strava:
return ActivityStravaViewController(activity: arg2)
}
}.inObjectScope(.transient)
return container
}()
With this approach, the named ActivityTabBarController
gets instantiated always by the activityPresentableContainer
using the following statement:
let controller = Containers.activityPresentableContainer.resolve(
ActivityTabBarController.self, argument: activity
)!
And then, each of the tabs inside the TabBarController gets instantiated using the required argument Activity
and the type of tab itself using a .transient
context. It resolves like this:
let activitySummary = Containers.activityPresentableContainer.resolve(
ActivityPresentable.self, arguments: ActivityPresentableTabs.summary, activity!
) as! UIViewController
This way I can generalize the tabs of the tab bar depending just on the information that they're using. If one of the tabs change in any moment, I can just change the registration, following the ActivityPresentable
protocol.