[Issue-21] Expose minimumTopOffset (#24)

* mark init(coder:) unavailable

* Better testing of typography and appearances

* Add minimum top offset to appearance

* Apply new sizing behavior and refactor to reduce file size

* Rename memory leak method

* Remove stray comment

Author: Mark Pospesel

Sources/YBottomSheet/BottomSheetController+Appearance.swift

@@ -28,6 +28,10 @@ extension BottomSheetController {
         public var presentAnimationCurve: UIView.AnimationOptions
         /// Animation type during dismissing. Default is `curveEaseOut`.
         public var dismissAnimationCurve: UIView.AnimationOptions
+        /// Minimum top offset of sheet from safe area top. Default is `44`.
+        ///
+        /// The top of the sheet will not move beyond this gap from the top of the safe area.
+        public var minimumTopOffset: CGFloat
         /// (Optional) Minimum content view height. Default is `nil`.
         ///
         /// Only applicable for resizable sheets. `nil` means to use the content view's intrinsic height as the minimum.
@@ -44,16 +48,17 @@ extension BottomSheetController {
 
         /// Initializes an `Appearance`.
         /// - Parameters:
-        ///   - indicatorAppearance: Appearance of the drag indicator or pass `nil` to hide.
-        ///   - headerAppearance: Appearance of the sheet header view or pass `nil` to hide.
-        ///   - layout: Bottom sheet layout properties such as corner radius.
-        ///   - elevation: Bottom sheet's shadow or pass `nil` to hide
-        ///   - dimmerColor: Dimmer view color or pass `nil` to hide.
-        ///   - animationDuration: Animation duration for bottom sheet. Default is `0.3`.
-        ///   - presentAnimationCurve: Animaiton during presenting.
-        ///   - dismissAnimationCurve: Animation during dismiss.
-        ///   - minimumContentHeight: Optional) Minimum content view height.
-        ///   - isDismissAllowed: Whether the sheet can be dismissed by swiping down or tapping on the dimmer.
+        ///   - indicatorAppearance: appearance of the drag indicator or pass `nil` to hide.
+        ///   - headerAppearance: appearance of the sheet header view or pass `nil` to hide.
+        ///   - layout: bottom sheet layout properties such as corner radius.
+        ///   - elevation: bottom sheet's shadow or pass `nil` to hide
+        ///   - dimmerColor: dimmer view color or pass `nil` to hide.
+        ///   - animationDuration: animation duration for bottom sheet. Default is `0.3`.
+        ///   - presentAnimationCurve: animation type during presenting.
+        ///   - dismissAnimationCurve: animation type during dismiss.
+        ///   - minimumTopOffset: minimum top offset. Default is `44`
+        ///   - minimumContentHeight: (optional) minimum content view height.
+        ///   - isDismissAllowed: whether the sheet can be dismissed by swiping down or tapping on the dimmer.
         public init(
             indicatorAppearance: DragIndicatorView.Appearance? = nil,
             headerAppearance: SheetHeaderView.Appearance? = .default,
@@ -63,6 +68,7 @@ extension BottomSheetController {
             animationDuration: TimeInterval = 0.3,
             presentAnimationCurve: UIView.AnimationOptions = .curveEaseIn,
             dismissAnimationCurve: UIView.AnimationOptions = .curveEaseOut,
+            minimumTopOffset: CGFloat = 44,
             minimumContentHeight: CGFloat? = nil,
             isDismissAllowed: Bool = true
         ) {
@@ -74,6 +80,7 @@ extension BottomSheetController {
             self.animationDuration = animationDuration
             self.presentAnimationCurve = presentAnimationCurve
             self.dismissAnimationCurve = dismissAnimationCurve
+            self.minimumTopOffset = minimumTopOffset
             self.minimumContentHeight = minimumContentHeight
             self.isDismissAllowed = isDismissAllowed
         }

Sources/YBottomSheet/BottomSheetController+build.swift

@@ -0,0 +1,94 @@
+//
+//  BottomSheetController+build.swift
+//  YBottomSheet
+//
+//  Created by Mark Pospesel on 4/26/23.
+//  Copyright © 2023 Y Media Labs. All rights reserved.
+//
+
+import UIKit
+
+internal extension BottomSheetController {
+    func build() {
+        switch content {
+        case .view(title: let title, view: let childView):
+            build(childView, title: title)
+        case .controller(let childController):
+            build(childController)
+        }
+    }
+}
+
+private extension BottomSheetController {
+    func build(_ subview: UIView, title: String) {
+        contentView.addSubview(subview)
+        subview.constrainEdges()
+
+        if let backgroundColor = subview.backgroundColor,
+           backgroundColor.rgbaComponents.alpha == 1 {
+            // use the subview's background color for the sheet
+            sheetView.backgroundColor = backgroundColor
+            // but we have to set the subview's background to nil or else
+            // it will overflow the sheet and not be cropped by the corner radius.
+            subview.backgroundColor = nil
+        }
+
+        indicatorView = DragIndicatorView(appearance: appearance.indicatorAppearance ?? .default)
+        indicatorContainer.addSubview(indicatorView)
+
+        headerView = SheetHeaderView(title: title, appearance: appearance.headerAppearance ?? .default)
+        headerView.delegate = self
+        buildSheet()
+    }
+
+    func build(_ childController: UIViewController) {
+        addChild(childController)
+        build(childController.view, title: childController.title ?? "")
+        childController.didMove(toParent: self)
+    }
+
+    func buildSheet() {
+        buildViews()
+        buildConstraints()
+        updateViewAppearance()
+        addGestures()
+    }
+
+    func buildViews() {
+        view.addSubview(dimmerView)
+        view.addSubview(dimmerTapView)
+        view.addSubview(sheetView)
+        sheetView.addSubview(stackView)
+        stackView.addArrangedSubview(indicatorContainer)
+        stackView.addArrangedSubview(headerView)
+        stackView.addArrangedSubview(contentView)
+    }
+
+    func buildConstraints() {
+        dimmerView.constrainEdges()
+        dimmerTapView.constrainEdges(.notBottom)
+        dimmerTapView.constrain(.bottomAnchor, to: sheetView.topAnchor)
+
+        sheetView.constrainEdges(.notTop)
+        minimumTopOffsetAnchor = sheetView.constrain(
+            .topAnchor,
+            to: view.safeAreaLayoutGuide.topAnchor,
+            relatedBy: .greaterThanOrEqual
+        )
+
+        indicatorView.constrain(.bottomAnchor, to: indicatorContainer.bottomAnchor)
+        indicatorTopAnchor = indicatorView.constrain(
+            .topAnchor,
+            to: indicatorContainer.topAnchor
+        )
+        indicatorView.constrainCenter(.x)
+
+        stackView.constrain(.topAnchor, to: sheetView.topAnchor)
+        stackView.constrainEdges(.horizontal, to: view.safeAreaLayoutGuide)
+        stackView.constrainEdges(.bottom, to: view.safeAreaLayoutGuide, relatedBy: .greaterThanOrEqual)
+        stackView.constrainEdges(.bottom, to: view.safeAreaLayoutGuide, priority: Priorities.sheetContentHugging)
+
+        contentView.constrainEdges(.horizontal)
+        headerView.constrainEdges(.horizontal)
+    }
+}

Sources/YBottomSheet/BottomSheetController.swift

@@ -10,17 +10,24 @@ import UIKit
 
 /// A view controller that manages a bottom sheet.
 public class BottomSheetController: UIViewController {
-    // Holds the sheet content until the view is loaded
-    private let content: Content
+    internal let content: Content
     private var shadowSize: CGSize = .zero
-    private let minimumTopOffset: CGFloat = 44
-    private let minimumContentHeight: CGFloat = 88
+    internal var minimumTopOffsetAnchor: NSLayoutConstraint?
     private var topAnchor: NSLayoutConstraint?
-    private var indicatorTopAnchor: NSLayoutConstraint?
+    internal var indicatorTopAnchor: NSLayoutConstraint?
     private var childHeightAnchor: NSLayoutConstraint?
     private var panGesture: UIPanGestureRecognizer?
     internal lazy var lastYOffset: CGFloat = { sheetView.frame.origin.y }()
 
+    /// Absolute minimum height of sheet content
+    ///
+    /// Only used when `appearance.minimumContentHeight == nil`.
+    public var minimumContentHeight: CGFloat = 88 {
+        didSet {
+            updateChildView()
+        }
+    }
+
     /// Minimum downward velocity beyond which we interpret a pan gesture as a downward swipe.
     public var dismissThresholdVelocity: CGFloat = 1000
 
@@ -42,11 +49,11 @@ public class BottomSheetController: UIViewController {
         return view
     }()
     /// Bottom sheet drag indicator view.
-    public private(set) var indicatorView: DragIndicatorView!
+    public internal(set) var indicatorView: DragIndicatorView!
     /// Container view for the drag indicator.
     internal let indicatorContainer = UIView()
     /// Bottom sheet header view.
-    public private(set) var headerView: SheetHeaderView!
+    public internal(set) var headerView: SheetHeaderView!
     /// Holds the sheet's child content (view or view controller).
     let contentView: UIView = {
         let view = UIView()
@@ -55,7 +62,7 @@ public class BottomSheetController: UIViewController {
     }()
 
     /// Comprises the indicator view, the header view, and the content view.
-    private let stackView: UIStackView = {
+    let stackView: UIStackView = {
         let stackView = UIStackView()
         stackView.axis = .vertical
         stackView.alignment = .center
@@ -119,8 +126,11 @@ public class BottomSheetController: UIViewController {
     }
 
     /// :nodoc:
-    internal required init?(coder: NSCoder) { nil }
-    
+    @available(*, unavailable)
+    required public init?(coder: NSCoder) {
+        fatalError("init(coder:) is not available for BottomSheetController")
+    }
+
     /// :nodoc:
     public override func viewDidLoad() {
         super.viewDidLoad()
@@ -159,105 +169,34 @@ public class BottomSheetController: UIViewController {
     }
 }
 
-private extension BottomSheetController {
-    func commonInit() {
-        modalPresentationStyle = .custom
-        transitioningDelegate = self
-    }
-
-    func build() {
-        switch content {
-        case .view(title: let title, view: let childView):
-            build(childView, title: title)
-        case .controller(let childController):
-            build(childController)
-        }
-    }
-
-    func build(_ subview: UIView, title: String) {
-        contentView.addSubview(subview)
-        subview.constrainEdges()
-
-        if let backgroundColor = subview.backgroundColor,
-           backgroundColor.rgbaComponents.alpha == 1 {
-            // use the subview's background color for the sheet
-            sheetView.backgroundColor = backgroundColor
-            // but we have to set the subview's background to nil or else
-            // it will overflow the sheet and not be cropped by the corner radius.
-            subview.backgroundColor = nil
-        }
-
-        indicatorView = DragIndicatorView(appearance: appearance.indicatorAppearance ?? .default)
-        indicatorContainer.addSubview(indicatorView)
-
-        headerView = SheetHeaderView(title: title, appearance: appearance.headerAppearance ?? .default)
-        headerView.delegate = self
-        buildSheet()
-    }
-    
-    func build(_ childController: UIViewController) {
-        addChild(childController)
-        build(childController.view, title: childController.title ?? "")
-        childController.didMove(toParent: self)
-    }
-    
-    func buildSheet() {
-        buildViews()
-        buildConstraints()
-        updateViewAppearance()
-        addGestures()
-    }
-
-    func buildViews() {
-        view.addSubview(dimmerView)
-        view.addSubview(dimmerTapView)
-        view.addSubview(sheetView)
-        sheetView.addSubview(stackView)
-        stackView.addArrangedSubview(indicatorContainer)
-        stackView.addArrangedSubview(headerView)
-        stackView.addArrangedSubview(contentView)
-    }
-
-    func buildConstraints() {
-        dimmerView.constrainEdges()
-        dimmerTapView.constrainEdges(.notBottom)
-        dimmerTapView.constrain(.bottomAnchor, to: sheetView.topAnchor)
-        
-        sheetView.constrainEdges(.notTop)
-        sheetView.constrain(
-            .topAnchor,
-            to: view.safeAreaLayoutGuide.topAnchor,
-            relatedBy: .greaterThanOrEqual,
-            constant: minimumTopOffset
-        )
-
-        indicatorView.constrain(.bottomAnchor, to: indicatorContainer.bottomAnchor)
-        indicatorTopAnchor = indicatorView.constrain(
-            .topAnchor,
-            to: indicatorContainer.topAnchor
-        )
-        indicatorView.constrainCenter(.x)
-
-        stackView.constrain(.topAnchor, to: sheetView.topAnchor)
-        stackView.constrainEdges(.horizontal, to: view.safeAreaLayoutGuide)
-        stackView.constrainEdges(.bottom, to: view.safeAreaLayoutGuide, relatedBy: .greaterThanOrEqual)
-        stackView.constrainEdges(.bottom, to: view.safeAreaLayoutGuide, priority: Priorities.sheetContentHugging)
-
-        contentView.constrainEdges(.horizontal)
-        headerView.constrainEdges(.horizontal)
-    }
-
+internal extension BottomSheetController {
     func updateViewAppearance() {
         dimmerTapView.isAccessibilityElement = appearance.isDismissAllowed
         sheetView.layer.cornerRadius = appearance.layout.cornerRadius
+        minimumTopOffsetAnchor?.constant = appearance.minimumTopOffset
         updateShadow()
         dimmerView.backgroundColor = appearance.dimmerColor
         updateIndicatorView()
         updateHeaderView()
         updateChildView()
         view.layoutIfNeeded()
     }
-    
+
+    func addGestures() {
+        let swipeGesture = UISwipeGestureRecognizer(target: self, action: #selector(onSwipeDown))
+        swipeGesture.direction = .down
+        view.addGestureRecognizer(swipeGesture)
+        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(onDimmerTap))
+        dimmerTapView.addGestureRecognizer(tapGesture)
+    }
+}
+
+private extension BottomSheetController {
+    func commonInit() {
+        modalPresentationStyle = .custom
+        transitioningDelegate = self
+    }
+
     func updateIndicatorView() {
         indicatorContainer.isHidden = !isResizable
         if let indicatorAppearance = appearance.indicatorAppearance {
@@ -313,14 +252,6 @@ private extension BottomSheetController {
     func updateShadow() {
         appearance.elevation?.apply(layer: sheetView.layer)
     }
-    
-    func addGestures() {
-        let swipeGesture = UISwipeGestureRecognizer(target: self, action: #selector(onSwipeDown))
-        swipeGesture.direction = .down
-        view.addGestureRecognizer(swipeGesture)
-        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(onDimmerTap))
-        dimmerTapView.addGestureRecognizer(tapGesture)
-    }
 
     func onDismiss() {
         dismiss(animated: true)

Sources/YBottomSheet/DragIndicatorView/DragIndicatorView.swift

@@ -34,7 +34,10 @@ open class DragIndicatorView: UIView {
     }
 
     /// :nodoc:
-    required public init?(coder: NSCoder) { nil }
+    @available(*, unavailable)
+    required public init?(coder: NSCoder) {
+        fatalError("init(coder:) is not available for DragIndicatorView")
+    }
 }
 
 private extension DragIndicatorView {

Sources/YBottomSheet/SheetHeaderView/SheetHeaderView.swift

@@ -48,8 +48,11 @@ open class SheetHeaderView: UIView {
     }
 
     /// :nodoc:
-    required public init?(coder: NSCoder) { nil }
-    
+    @available(*, unavailable)
+    required public init?(coder: NSCoder) {
+        fatalError("init(coder:) is not available for SheetHeaderView")
+    }
+
     @objc private func closeButtonAction() {
         delegate?.didTapCloseButton()
     }

Tests/YBottomSheetTests/Animation/BottomSheetAnimatorTests.swift

@@ -46,7 +46,7 @@ private extension BottomSheetAnimatorTests {
         line: UInt = #line
     ) -> BottomSheetAnimator {
         let sut = BottomSheetAnimator(sheetViewController: sheetViewController)
-        trackForMemoryLeaks(sut, file: file, line: line)
+        trackForMemoryLeak(sut, file: file, line: line)
         return sut
     }
 }