Merge pull request #17 from inloop/feature/uistackview-support

NEW FEATURE: Embed to UIStackView

CHANGELOG.md

@@ -1,3 +1,7 @@
+## [2.1.0]
+### Added
+- `UIStackView` support. You can now use `UIStackView` as a container, and you can insert child's view with animation if you wish. `UIStackView` is a great help, especially if you have multiple childs. You no longer need to set them constraints - `UIStackView` + autolayout will do this for you.
+
 ## [2.0.0]
 ### Changed
 - lib uses Swift 4.2 internally

UIViewController-DisplayChild.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'UIViewController-DisplayChild'
-  s.version          = '2.0.0'
+  s.version          = '2.1.0'
   s.summary          = 'UIViewController containment made easy'
   s.description      = <<-DESC
   The problem: sometimes you need to embed a controller, but it might be embedded already. E.g. you have an empty view, and you do refresh only to get empty view again. If you do not check for its existence, you might end up creating a new instance unneccessarily. This can also have bad side effects when there is some heavier work in viewDidLoad for example.

UIViewController-DisplayChild/UIViewController+DisplayChild.swift

@@ -24,12 +24,11 @@ public extension UIViewController {
      - Parameter completion: a closure which is called after the child view controller presentation is finished.
      - Returns: Newly created and embedded or already existing controller of specified type.
      */
-    @discardableResult func displayChild<T: UIViewController & Instantiable>(
-        ofType viewControllerType: T.Type,
-        in optionalContainerView: UIView? = nil,
-        animated: Bool = true,
-        configuration: ((T) -> Void)? = nil,
-        completion: ((T) -> Void)? = nil) -> T {
+    @discardableResult func displayChild<T: UIViewController & Instantiable>(ofType viewControllerType: T.Type,
+                                                                             in optionalContainerView: UIView? = nil,
+                                                                             animated: Bool = true,
+                                                                             configuration: ((T) -> Void)? = nil,
+                                                                             completion: ((T) -> Void)? = nil) -> T {
 
         let result: T
         let containerView = optionalContainerView ?? view!
@@ -48,6 +47,53 @@ public extension UIViewController {
         return result
     }
 
+    /**
+     Detects if a child view controller of specified type is already embedded in stack view.
+     If it is, configuration and completion closures are called on existing and this one is returned.
+     If it does not exist yet, it is instantiated, configured and embedded in specified container view.
+     - Parameter ofType: a view controller type to embed
+     - Parameter in: a stack view to embed child to.
+     - Parameter at: index of stackView's arrangedSubviews, where to insert. Will append, if `nil`.
+     - Parameter animated: insertion is animated if `true`
+     - Parameter configuration: a closure which is called after the controller is initialized.
+     This is where you can configure the controller before presenting.
+     - Parameter completion: a closure which is called after the child view controller presentation is finished.
+     - Returns: Newly created and embedded or already existing controller of specified type.
+     */
+    @discardableResult func insertChild<T: UIViewController & Instantiable>(ofType viewControllerType: T.Type,
+                                                                            in stackView: UIStackView,
+                                                                            at index: Int? = nil,
+                                                                            animated: Bool,
+                                                                            configuration: ((T) -> Void)? = nil,
+                                                                            completion: ((T) -> Void)? = nil) -> T {
+        let result: T
+        if let existingController: T = childViewController(in: stackView, at: index) {
+            configuration?(existingController)
+            completion?(existingController)
+            result = existingController
+        } else {
+            result = viewControllerType.makeInstance()
+            configuration?(result)
+            addChild(result)
+            if animated {
+                result.view.isHidden = true
+                stackView.addSubview(result.view, at: index)
+                UIView.animate(
+                    withDuration: UIViewController.embedTransitionAnimationDuration,
+                    animations: { result.view.isHidden = false },
+                    completion: { _ in
+                        result.didMove(toParent: self)
+                        completion?(result)
+                })
+            } else {
+                stackView.addSubview(result.view, at: index)
+                result.didMove(toParent: self)
+                completion?(result)
+            }
+        }
+        return result
+    }
+
     private func presentedController(with newController: UIViewController) -> UIViewController {
         return newController.navigationController ?? newController
     }
@@ -103,6 +149,25 @@ public extension UIViewController {
         child?.removeFromParent()
     }
 
+    func removeChildViewController<T: UIViewController>(ofType viewControllerType: T.Type,
+                                                        from stackView: UIStackView,
+                                                        at index: Int? = nil,
+                                                        animated: Bool) {
+        guard let child: T = childViewController(in: stackView, at: index) else { return }
+        child.willMove(toParent: nil)
+        if animated {
+            UIView.animate(withDuration: UIViewController.embedTransitionAnimationDuration,
+                           animations: { child.view.isHidden = true },
+                           completion: { _ in
+                            child.view.removeFromSuperview()
+                            child.removeFromParent()
+            })
+        } else {
+            child.view.removeFromSuperview()
+            child.removeFromParent()
+        }
+    }
+
     func childViewController<T>(in optionalContainerView: UIView? = nil) -> T? {
         let containerView = optionalContainerView ?? view!
         let result: T?
@@ -118,6 +183,33 @@ public extension UIViewController {
         return result
     }
 
+    /**
+     Finds a child view controller of type T, whose view is in arranged subviews in UIStackView at specified index.
+     If you are sure that there is only one child controller of this type in a stack view you can omit the index
+     parameter and the method returns the first controller it finds.
+     - Parameter in: a stack view to search in
+     - Parameter at: optional index in stackView's `arrangedSubviews`.
+     - Returns: child view controller of type T, whose view is in arranged subviews in UIStackView at specified index.
+     If index is `nil` it is the first child of type T encountered.
+     */
+    func childViewController<T>(in stackView: UIStackView, at index: Int? = nil) -> T? {
+        if let index = index {
+            guard index < stackView.arrangedSubviews.count else { return nil }
+            let view = stackView.arrangedSubviews[index]
+            let child = children.first(where: { $0.view == view})
+            return child as? T
+        } else {
+            var result: T?
+            stackView.arrangedSubviews.forEach { view in
+                let child = children.first(where: { $0.view == view})
+                if let searchResult = child as? T {
+                    result = searchResult
+                }
+            }
+            return result
+        }
+    }
+
     func hasChild<T>(ofType controllerType: T.Type, in optionalContainerView: UIView? = nil) -> Bool {
         let exists: T? = childViewController(in: optionalContainerView)
         return exists != nil
@@ -161,3 +253,13 @@ private extension UINavigationController {
         return result
     }
 }
+
+private extension UIStackView {
+    func addSubview(_ view: UIView, at index: Int?) {
+        if let index = index {
+            insertArrangedSubview(view, at: index)
+        } else {
+            addArrangedSubview(view)
+        }
+    }
+}