SheetImagePicker.xcodeproj/project.pbxproj

@@ -18,7 +18,6 @@
 		D610D2F6233945C0009EB06A /* SheetImagePicker.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = D610D2D1233945AF009EB06A /* SheetImagePicker.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		D610D2FD23394E00009EB06A /* SheetContainerViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D610D2FC23394E00009EB06A /* SheetContainerViewController.swift */; };
 		D610D2FF23395975009EB06A /* Detent.swift in Sources */ = {isa = PBXBuildFile; fileRef = D610D2FE23395975009EB06A /* Detent.swift */; };
-		D6B61D63233A748300809DE7 /* MathHelpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6B61D62233A748300809DE7 /* MathHelpers.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -59,7 +58,6 @@
 		D610D2F0233945BB009EB06A /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		D610D2FC23394E00009EB06A /* SheetContainerViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SheetContainerViewController.swift; sourceTree = "<group>"; };
 		D610D2FE23395975009EB06A /* Detent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Detent.swift; sourceTree = "<group>"; };
-		D6B61D62233A748300809DE7 /* MathHelpers.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MathHelpers.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -104,7 +102,6 @@
 			isa = PBXGroup;
 			children = (
 				D610D2D4233945AF009EB06A /* SheetImagePicker.h */,
-				D6B61D62233A748300809DE7 /* MathHelpers.swift */,
 				D610D2FC23394E00009EB06A /* SheetContainerViewController.swift */,
 				D610D2FE23395975009EB06A /* Detent.swift */,
 				D610D2D5233945AF009EB06A /* Info.plist */,
@@ -249,7 +246,6 @@
 			files = (
 				D610D2FD23394E00009EB06A /* SheetContainerViewController.swift in Sources */,
 				D610D2FF23395975009EB06A /* Detent.swift in Sources */,
-				D6B61D63233A748300809DE7 /* MathHelpers.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

SheetImagePicker/Detent.swift

@@ -8,7 +8,7 @@
 
 import UIKit
 
-public enum Detent: Equatable {
+public enum Detent {
     case top
     case middle
     case bottom

SheetImagePicker/MathHelpers.swift

@@ -1,30 +0,0 @@
-//
-//  MathHelpers.swift
-//  SheetImagePicker
-//
-//  Created by Shadowfacts on 9/24/19.
-//  Copyright © 2019 Shadowfacts. All rights reserved.
-//
-
-import UIKit
-
-func clamp(_ value: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
-    if value < from {
-        return from
-    } else if value > to {
-        return to
-    } else {
-        return value
-    }
-}
-
-func smoothstep(value: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
-    let x = clamp((value - from) / (to - from), from: 0, to: 1)
-    // 3x^2 - 2x^3
-    return 3 * pow(x, 2) - 2 * pow(x, 3)
-}
-
-func lerp(_ value: CGFloat, min: CGFloat, max: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
-    let value = clamp((value - min) / (max - min), from: 0, to: 1)
-    return value * (to - from) + from
-}

SheetImagePicker/SheetContainerViewController.swift

@@ -8,42 +8,22 @@
 
 import UIKit
 
-public protocol SheetContainerViewControllerDelegate {
-    func sheetContainer(_ sheetContainer: SheetContainerViewController, willSnapToDetent detent: Detent) -> Bool
-    func sheetContainer(_ sheetContainer: SheetContainerViewController, didSnapToDetent detent: Detent)
-}
-
-// default no-op implementation
-public extension SheetContainerViewControllerDelegate {
-    func sheetContainer(_ sheetContainer: SheetContainerViewController, willSnapToDetent detent: Detent) -> Bool {
-        return true
-    }
-    func sheetContainer(_ sheetContainer: SheetContainerViewController, didSnapToDetent detent: Detent) {}
-}
-
 public class SheetContainerViewController: UIViewController {
 
-    public var delegate: SheetContainerViewControllerDelegate?
-    
     let content: UIViewController
     
-    public var detents: [Detent] = [.bottom, .middle, .top]
+    public var detents: [Detent] = [.bottom, .middle, .top] {
-    var topDetent: (detent: Detent, offset: CGFloat) {
+        didSet {
-        return detents.map { ($0, $0.offset(in: view)) }.min(by: { $0.1 < $1.1 })!
+            sortDetents()
         }
-    var bottomDetent: (detent: Detent, offset: CGFloat) {
-        return detents.map { ($0, $0.offset(in: view)) }.max(by: { $0.1 < $1.1 })!
     }
-    
+    var sortedDetentOffsets: [CGFloat] = []
-    public var minimumDetentJumpVelocity: CGFloat = 500
-    public var maximumStretchDistance: CGFloat = 15
 
     var topConstraint: NSLayoutConstraint!
     lazy var initialConstant: CGFloat = view.bounds.height / 2
     
-    var dimmingView: UIView!
+    public var minimumDetentJumpVelocity: CGFloat = 500
-    public var minimumDimmingAlpha: CGFloat = 0
+    public var maximumStretchDistance: CGFloat = 15
-    public var maximumDimmingAlpha: CGFloat = 0.75
     
     public init(content: UIViewController) {
         self.content = content
@@ -58,18 +38,6 @@ public class SheetContainerViewController: UIViewController {
     override public func viewDidLoad() {
         super.viewDidLoad()
         
-        dimmingView = UIView()
-        dimmingView.translatesAutoresizingMaskIntoConstraints = false
-        dimmingView.backgroundColor = .systemGray
-        dimmingView.alpha = (maximumDimmingAlpha - minimumDimmingAlpha) / 2
-        view.addSubview(dimmingView)
-        NSLayoutConstraint.activate([
-            dimmingView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
-            dimmingView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
-            dimmingView.topAnchor.constraint(equalTo: view.topAnchor),
-            dimmingView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
-        ])
-        
         addChild(content)
         content.didMove(toParent: self)
         view.addSubview(content.view)
@@ -85,6 +53,18 @@ public class SheetContainerViewController: UIViewController {
         content.view.addGestureRecognizer(panGesture)
     }
     
+    public override func viewDidLayoutSubviews() {
+        super.viewDidLayoutSubviews()
+        
+        sortDetents()
+    }
+    
+    private func sortDetents() {
+        sortedDetentOffsets = detents.map {
+            $0.offset(in: view)
+        }.sorted()
+    }
+    
     @objc func panGestureRecognized(_ recognizer: UIPanGestureRecognizer) {
         switch recognizer.state {
         case .began:
@@ -93,59 +73,62 @@ public class SheetContainerViewController: UIViewController {
         case .changed:
             let translation = recognizer.translation(in: content.view)
             var realOffset = initialConstant + translation.y
-            let topOffset = topDetent.offset
+            if realOffset < sortedDetentOffsets.first! {
-            if realOffset < topOffset {
+                func clamp(_ value: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
+                    if value < from {
+                        return from
+                    } else if value > to {
+                        return to
+                    } else {
+                        return value
+                    }
+                }
+                func smoothstep(value: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
+                    let x = clamp((value - from) / (to - from), from: 0, to: 1)
+                    // 3x^2 - 2x^3
+                    return 3 * pow(x, 2) - 2 * pow(x, 3)
+                }
+                let topOffset = sortedDetentOffsets.first!
                 let smoothed = smoothstep(value: realOffset, from: topOffset, to: 0)
                 realOffset = topOffset - smoothed * maximumStretchDistance
                 
             }
             topConstraint.constant = realOffset
-            dimmingView.alpha = lerp(realOffset, min: topOffset, max: bottomDetent.offset, from: maximumDimmingAlpha, to: minimumDimmingAlpha)
             
         case .ended:
             let velocity = recognizer.velocity(in: view)
 
-            let springToDetent: (Detent, CGFloat)
+            let springToDetent: CGFloat
             if abs(velocity.y) > minimumDetentJumpVelocity,
-                let detentInVelocityDirection = nearestDetentOffset(currentOffset: topConstraint.constant, direction: velocity.y) {
+                let offsetInVelocityDirection = nearestDetentOffset(currentOffset: topConstraint.constant, direction: velocity.y) {
-                springToDetent = detentInVelocityDirection
+                springToDetent = offsetInVelocityDirection
-            } else if let nearestDetent = nearestDetentOffset(currentOffset: topConstraint.constant) {
+            } else if let nearestOffset = nearestDetentOffset(currentOffset: topConstraint.constant) {
-                springToDetent = nearestDetent
+                springToDetent = nearestOffset
             } else {
                 return
             }
             
-            if delegate?.sheetContainer(self, willSnapToDetent: springToDetent.0) ?? true {
+            let springDistance = abs(topConstraint.constant - springToDetent)
-                let springDistance = abs(topConstraint.constant - springToDetent.1)
+            self.topConstraint.constant = springToDetent
-                self.topConstraint.constant = springToDetent.1
             let springVelocity = velocity.y / springDistance
             
             UIView.animate(withDuration: 0.35, delay: 0, usingSpringWithDamping: 0.6, initialSpringVelocity: springVelocity, animations: {
                 self.view.layoutIfNeeded()
-                    self.dimmingView.alpha = lerp(springToDetent.1, min: self.topDetent.offset, max: self.bottomDetent.offset, from: self.maximumDimmingAlpha, to: self.minimumDimmingAlpha)
-                }, completion: { (finished) in
-                    self.delegate?.sheetContainer(self, didSnapToDetent: springToDetent.0)
             })
-            }
         default:
             return
         }
     }
     
-    func nearestDetentOffset(currentOffset: CGFloat) -> (Detent, CGFloat)? {
+    func nearestDetentOffset(currentOffset: CGFloat) -> CGFloat? {
-        return detents.map { ($0, $0.offset(in: view)) }.min { (a, b) -> Bool in
+        return sortedDetentOffsets.min(by: { abs($0 - currentOffset) < abs($1 - currentOffset) })
-            return abs(a.1 - currentOffset) < abs(b.1 - currentOffset)
-        }
     }
     
-    func nearestDetentOffset(currentOffset: CGFloat, direction: CGFloat) -> (Detent, CGFloat)? {
+    func nearestDetentOffset(currentOffset: CGFloat, direction: CGFloat) -> CGFloat? {
-        let sorted = detents.map { ($0, $0.offset(in: view)) }.sorted { (a, b) -> Bool in
-            return a.1 < b.1
-        }
         if direction < 0 {
-            return sorted.last(where: { $0.1 < currentOffset })
+            return sortedDetentOffsets.last(where: { $0 < currentOffset })
         } else {
-            return sorted.first(where: { $0.1 > currentOffset })
+            return sortedDetentOffsets.first(where: { $0 > currentOffset })
         }
     }
     

SheetImagePickerTest/ViewController.swift

@@ -14,15 +14,12 @@ class ViewController: UIViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
         // Do any additional setup after loading the view.
-        view.backgroundColor = .green
         
         let content = UIViewController()
         content.view.translatesAutoresizingMaskIntoConstraints = false
         content.view.backgroundColor = .red
         let sheet = SheetContainerViewController(content: content)
-        sheet.delegate = self
+        sheet.view.backgroundColor = .blue
-        sheet.detents = [.bottom, .middle, .top]
-//        sheet.view.backgroundColor = .blue
         
         addChild(sheet)
         sheet.didMove(toParent: self)
@@ -37,18 +34,3 @@ class ViewController: UIViewController {
 
 }
 
-extension ViewController: SheetContainerViewControllerDelegate {
-    func sheetContainer(_ sheetContainer: SheetContainerViewController, willSnapToDetent detent: Detent) -> Bool {
-        if detent == .bottom {
-            UIView.animate(withDuration: 0.35, animations: {
-                sheetContainer.view.transform = CGAffineTransform(translationX: 0, y: sheetContainer.view.bounds.height)
-            }, completion: { (finished) in
-                sheetContainer.removeFromParent()
-                sheetContainer.didMove(toParent: nil)
-                sheetContainer.view.removeFromSuperview()
-            })
-            return false
-        }
-        return true
-    }
-}