Add support for scroll views inside of navigation controllers

SheetImagePicker/SheetContainerViewController.swift

@@ -11,6 +11,8 @@ import UIKit
 public protocol SheetContainerViewControllerDelegate {
     func sheetContainer(_ sheetContainer: SheetContainerViewController, willSnapToDetent detent: Detent) -> Bool
     func sheetContainer(_ sheetContainer: SheetContainerViewController, didSnapToDetent detent: Detent)
+    func sheetContainerContentScrollView(_ sheetContainer: SheetContainerViewController) -> UIScrollView?
+    func sheetContainer(_ sheetContainer: SheetContainerViewController, topContentOffsetForScrollView scrollView: UIScrollView) -> CGFloat
 }
 
 // default no-op implementation
@@ -19,13 +21,19 @@ public extension SheetContainerViewControllerDelegate {
         return true
     }
     func sheetContainer(_ sheetContainer: SheetContainerViewController, didSnapToDetent detent: Detent) {}
+    func sheetContainerContentScrollView(_ sheetContainer: SheetContainerViewController) -> UIScrollView? {
+        return nil
+    }
+    func sheetContainer(_ sheetContainer: SheetContainerViewController, topContentOffsetForScrollView scrollView: UIScrollView) -> CGFloat {
+        return 0
+    }
 }
 
 public class SheetContainerViewController: UIViewController {
 
     public var delegate: SheetContainerViewControllerDelegate?
     
-    let content: UIViewController
+    public let content: UIViewController
     
     public var detents: [Detent] = [.bottom, .middle, .top]
     var topDetent: (detent: Detent, offset: CGFloat) {
@@ -44,7 +52,10 @@ public class SheetContainerViewController: UIViewController {
     var dimmingView: UIView!
     public var minimumDimmingAlpha: CGFloat = 0
     public var maximumDimmingAlpha: CGFloat = 0.75
-    var initialScrollViewContentOffset = CGPoint.zero
+    
+    var contentScrollView: UIScrollView? {
+        delegate?.sheetContainerContentScrollView(self) ?? content.view as? UIScrollView
+    }
 
     public init(content: UIViewController) {
         self.content = content
@@ -85,11 +96,12 @@ public class SheetContainerViewController: UIViewController {
             dimmingView.bottomAnchor.constraint(equalTo: content.view.topAnchor, constant: content.view.layer.cornerRadius)
         ])
         
-        if let scrollView = content.view as? UIScrollView {
+        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(panGestureRecognized(_:)))
+        panGesture.delegate = self
+        content.view.addGestureRecognizer(panGesture)
+        
+        if let scrollView = contentScrollView {
             scrollView.panGestureRecognizer.addTarget(self, action: #selector(scrollViewPanGestureRecognized))
-        } else {
-            let panGesture = UIPanGestureRecognizer(target: self, action: #selector(panGestureRecognized(_:)))
-            content.view.addGestureRecognizer(panGesture)
         }
     }
 
@@ -115,26 +127,24 @@ public class SheetContainerViewController: UIViewController {
     @objc func scrollViewPanGestureRecognized(_ recognizer: UIPanGestureRecognizer) {
         guard let scrollView = recognizer.view as? UIScrollView else { return }
 
-        let translation = recognizer.translation(in: scrollView)
         let velocity = recognizer.velocity(in: scrollView)
 
-        let shouldMoveSheetDown = scrollView.contentOffset.y <= 0 && velocity.y > 0 // scrolled to top and dragging down
+        let topContentOffset: CGFloat = delegate?.sheetContainer(self, topContentOffsetForScrollView: scrollView) ?? 0
+        let shouldMoveSheetDown = scrollView.contentOffset.y <= topContentOffset && velocity.y > 0 // scrolled to top and dragging down
         let shouldMoveSheetUp = topConstraint.constant > topDetent.offset && velocity.y < 0 // not fully expanded and dragging up
 
         let shouldMoveSheet = shouldMoveSheetDown || shouldMoveSheetUp
         if shouldMoveSheet {
             scrollView.bounces = false
-            scrollView.setContentOffset(.zero, animated: false)
+            scrollView.setContentOffset(CGPoint(x: 0, y: topContentOffset), animated: false)
         }
 
         switch recognizer.state {
-        case .began:
-            initialScrollViewContentOffset = scrollView.contentOffset
-            
         case .changed:
             if shouldMoveSheet {
+                let translation = recognizer.translation(in: scrollView)
                 setTopOffset(topConstraint.constant + translation.y)
-                recognizer.setTranslation(initialScrollViewContentOffset, in: scrollView)
+                recognizer.setTranslation(.zero, in: scrollView)
             }
 
         case .ended:
@@ -205,6 +215,15 @@ public class SheetContainerViewController: UIViewController {
     
 }
 
+extension SheetContainerViewController: UIGestureRecognizerDelegate {
+    public func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
+        if topConstraint.constant <= topDetent.offset {
+            return (gestureRecognizer as! UIPanGestureRecognizer).translation(in: gestureRecognizer.view!).y > 0
+        }
+        return true
+    }
+}
+
 extension SheetContainerViewController: UIViewControllerTransitioningDelegate {
     public func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
         return SheetContainerPresentationAnimationController()

SheetImagePickerTest/Base.lproj/Main.storyboard

@@ -16,29 +16,36 @@
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" translatesAutoresizingMaskIntoConstraints="NO" id="hIF-hV-InX">
-                                <rect key="frame" x="188.5" y="403" width="37" height="90"/>
+                                <rect key="frame" x="173" y="388" width="68" height="120"/>
                                 <subviews>
                                     <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="tfd-T0-fMO">
-                                        <rect key="frame" x="0.0" y="0.0" width="37" height="30"/>
+                                        <rect key="frame" x="0.0" y="0.0" width="68" height="30"/>
                                         <state key="normal" title="Plain"/>
                                         <connections>
                                             <action selector="plainPressed:" destination="BYZ-38-t0r" eventType="touchUpInside" id="tmi-VL-j61"/>
                                         </connections>
                                     </button>
                                     <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="fT8-yG-J2R">
-                                        <rect key="frame" x="0.0" y="30" width="37" height="30"/>
+                                        <rect key="frame" x="0.0" y="30" width="68" height="30"/>
                                         <state key="normal" title="Table"/>
                                         <connections>
                                             <action selector="tablePressed:" destination="BYZ-38-t0r" eventType="touchUpInside" id="PZl-oC-0t4"/>
                                         </connections>
                                     </button>
                                     <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="39x-b2-4Hx">
-                                        <rect key="frame" x="0.0" y="60" width="37" height="30"/>
+                                        <rect key="frame" x="0.0" y="60" width="68" height="30"/>
                                         <state key="normal" title="Nav"/>
                                         <connections>
                                             <action selector="navPressed:" destination="BYZ-38-t0r" eventType="touchUpInside" id="Jc9-R9-VZW"/>
                                         </connections>
                                     </button>
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="eUF-7N-Qgr">
+                                        <rect key="frame" x="0.0" y="90" width="68" height="30"/>
+                                        <state key="normal" title="Nav Table"/>
+                                        <connections>
+                                            <action selector="navTablePressed:" destination="BYZ-38-t0r" eventType="touchUpInside" id="fSY-4h-jE3"/>
+                                        </connections>
+                                    </button>
                                 </subviews>
                             </stackView>
                         </subviews>

SheetImagePickerTest/ContentTableViewController.swift

@@ -40,4 +40,21 @@ class ContentTableViewController: UITableViewController {
         
         return cell
     }
+    
+    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
+        guard let navController = navigationController else { return }
+        
+        let vc = UIViewController()
+        vc.view.backgroundColor = .systemBackground
+        let label = UILabel()
+        label.translatesAutoresizingMaskIntoConstraints = false
+        label.text = "\(indexPath.row)"
+        vc.view.addSubview(label)
+        NSLayoutConstraint.activate([
+            label.centerXAnchor.constraint(equalTo: vc.view.centerXAnchor),
+            label.centerYAnchor.constraint(equalTo: vc.view.centerYAnchor)
+        ])
+
+        navController.pushViewController(vc, animated: true)
+    }
 }

SheetImagePickerTest/ViewController.swift

@@ -58,6 +58,42 @@ class ViewController: UIViewController {
     }
     
     @IBAction func navPressed(_ sender: Any) {
+        let root = UIViewController()
+        root.view.backgroundColor = .systemBackground
+        let label = UILabel()
+        label.text = "Root VC"
+        label.translatesAutoresizingMaskIntoConstraints = false
+        root.view.addSubview(label)
+        NSLayoutConstraint.activate([
+            label.centerXAnchor.constraint(equalTo: root.view.centerXAnchor),
+            label.centerYAnchor.constraint(equalTo: root.view.centerYAnchor)
+        ])
+        
+        let nav = UINavigationController(rootViewController: root)
+        nav.view.translatesAutoresizingMaskIntoConstraints = false
+        nav.view.layer.masksToBounds = true
+        nav.view.layer.cornerRadius = view.bounds.width * 0.02
+
+        let sheet = SheetContainerViewController(content: nav)
+        sheet.delegate = self
+        sheet.detents = [.bottom, .middle, .top]
+        
+        present(sheet, animated: true)
+    }
+    
+    @IBAction func navTablePressed(_ sender: Any) {
+        let table = ContentTableViewController()
+        
+        let nav = UINavigationController(rootViewController: table)
+        nav.view.translatesAutoresizingMaskIntoConstraints = false
+        nav.view.layer.masksToBounds = true
+        nav.view.layer.cornerRadius = view.bounds.width * 0.02
+        
+        let sheet = SheetContainerViewController(content: nav)
+        sheet.delegate = self
+        sheet.detents = [.bottom, .middle, .top]
+        
+        present(sheet, animated: true)
     }
 }
 
@@ -69,4 +105,18 @@ extension ViewController: SheetContainerViewControllerDelegate {
         }
         return true
     }
+    func sheetContainerContentScrollView(_ sheetContainer: SheetContainerViewController) -> UIScrollView? {
+        if let navController = sheetContainer.content as? UINavigationController, let scrollView = navController.visibleViewController?.view as? UIScrollView {
+            return scrollView
+        } else {
+            return nil
+        }
+    }
+    func sheetContainer(_ sheetContainer: SheetContainerViewController, topContentOffsetForScrollView scrollView: UIScrollView) -> CGFloat {
+        if let navController = sheetContainer.content as? UINavigationController, navController.visibleViewController?.view is UIScrollView {
+            return -navController.navigationBar.bounds.height
+        } else {
+            return 0
+        }
+    }
 }