Merge pull request #51 from componentskit/fix/modal-keyboard-interaction

adapt modal position when a keyboard appears / disappears

Author: mikhailChelbaev

Examples/DemosApp/DemosApp/ComponentsPreview/Helpers/ModalPreview+Helpers.swift

@@ -194,6 +194,7 @@ Enim habitant laoreet inceptos scelerisque senectus, tellus molestie ut. Eros ri
         HStack {
           Text(self.headerTitle)
             .font(self.headerFont.font)
+          Spacer()
         }
       } else {
         EmptyView()
@@ -211,6 +212,7 @@ Enim habitant laoreet inceptos scelerisque senectus, tellus molestie ut. Eros ri
       }
     }
     .font(self.bodyFont.font)
+    .multilineTextAlignment(.leading)
   }
 
   static func suFooter(

Sources/ComponentsKit/Components/Modal/SwiftUI/ModalContent.swift

@@ -24,10 +24,7 @@ struct ModalContent<VM: ModalVM, Header: View, Body: View, Footer: View>: View {
   }
 
   var body: some View {
-    VStack(
-      alignment: .leading,
-      spacing: self.model.contentSpacing
-    ) {
+    VStack(spacing: self.model.contentSpacing) {
       self.contentHeader()
         .observeSize {
           self.headerSize = $0

Sources/ComponentsKit/Components/Modal/UIKit/UKBottomModalController.swift

@@ -95,7 +95,7 @@ public class UKBottomModalController: UKModalController<BottomModalVM> {
   public override func layout() {
     super.layout()
 
-    self.contentView.bottom(self.model.outerPaddings.bottom, safeArea: true)
+    self.contentViewBottomConstraint = self.contentView.bottom(self.model.outerPaddings.bottom, safeArea: true).bottom
   }
 
   // MARK: - UIViewController Methods

Sources/ComponentsKit/Components/Modal/UIKit/UKCenterModalController.swift

@@ -88,11 +88,15 @@ public class UKCenterModalController: UKModalController<CenterModalVM> {
   public override func layout() {
     super.layout()
 
-    self.contentView.bottomAnchor.constraint(
+    self.contentViewBottomConstraint = self.contentView.bottomAnchor.constraint(
       lessThanOrEqualTo: self.view.safeAreaLayoutGuide.bottomAnchor,
       constant: -self.model.outerPaddings.bottom
-    ).isActive = true
-    self.contentView.centerVertically()
+    )
+    self.contentViewBottomConstraint?.isActive = true
+
+    let verticalConstraint = self.contentView.centerYAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.centerYAnchor)
+    verticalConstraint.isActive = true
+    verticalConstraint.priority = .defaultLow
   }
 
   // MARK: - UIViewController Methods

Sources/ComponentsKit/Components/Modal/UIKit/UKModalController.swift

@@ -15,6 +15,7 @@ open class UKModalController<VM: ModalVM>: UIViewController {
   public let model: VM
 
   private var contentViewWidthConstraint: NSLayoutConstraint?
+  var contentViewBottomConstraint: NSLayoutConstraint?
 
   // MARK: - Subviews
 
@@ -53,6 +54,12 @@ open class UKModalController<VM: ModalVM>: UIViewController {
     fatalError("init(coder:) has not been implemented")
   }
 
+  // MARK: Deinitialization
+
+  deinit {
+    NotificationCenter.default.removeObserver(self)
+  }
+
   // MARK: - Lifecycle
 
   open override func viewDidLoad() {
@@ -65,7 +72,7 @@ open class UKModalController<VM: ModalVM>: UIViewController {
 
   // MARK: - Setup
 
-  /// Sets up the modal's subviews and gesture recognizers.
+  /// Sets up the modal's subviews, gesture recognizers and observers.
   open func setup() {
     self.view.addSubview(self.overlay)
     self.view.addSubview(self.contentView)
@@ -89,13 +96,45 @@ open class UKModalController<VM: ModalVM>: UIViewController {
         controller.handleTraitChanges()
       }
     }
+
+    NotificationCenter.default.addObserver(
+      self,
+      selector: #selector(self.handleKeyboardWillShow),
+      name: UIResponder.keyboardWillShowNotification,
+      object: nil
+    )
+
+    NotificationCenter.default.addObserver(
+      self,
+      selector: #selector(self.handleKeyboardWillHide),
+      name: UIResponder.keyboardWillHideNotification,
+      object: nil
+    )
   }
 
   @objc func handleOverlayTap() {
     guard self.model.closesOnOverlayTap else { return }
     self.dismiss(animated: true)
   }
 
+  @objc func handleKeyboardWillShow(notification: NSNotification) {
+    if let keyboardHeight = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue.height {
+      let duration = notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? CGFloat ?? 0.25
+      UIView.animate(withDuration: duration) {
+        self.contentViewBottomConstraint?.constant = -keyboardHeight - self.model.contentPaddings.bottom + self.view.safeAreaInsets.bottom
+        self.view.layoutIfNeeded()
+      }
+    }
+  }
+
+  @objc func handleKeyboardWillHide(notification: NSNotification) {
+    let duration = notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? CGFloat ?? 0.25
+    UIView.animate(withDuration: duration) {
+      self.contentViewBottomConstraint?.constant = -self.model.contentPaddings.bottom
+      self.view.layoutIfNeeded()
+    }
+  }
+
   // MARK: - Style
 
   /// Applies styling to the modal's subviews.