development: added PanController

Material.xcodeproj/project.pbxproj

@@ -176,6 +176,7 @@
 		96BFC1541E5E486F0075DE1F /* SpringAnimation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 965532281E47E388005C2792 /* SpringAnimation.swift */; };
 		96BFC16F1E63C10A0075DE1F /* SpringAnimation.swift in Headers */ = {isa = PBXBuildFile; fileRef = 965532281E47E388005C2792 /* SpringAnimation.swift */; settings = {ATTRIBUTES = (Public, ); }; };
 		96D88C321C1328D800B91418 /* Material.h in Headers */ = {isa = PBXBuildFile; fileRef = 96D88C091C1328D800B91418 /* Material.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		96DE566C1EF1B63B006DA70E /* PanController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96DE566B1EF1B63B006DA70E /* PanController.swift */; };
 		96E3C3951D3A1CC20086A024 /* IconButton.swift in Headers */ = {isa = PBXBuildFile; fileRef = 9658F2161CD6FA4700B902C1 /* IconButton.swift */; settings = {ATTRIBUTES = (Public, ); }; };
 		96E3C3961D3A1CC20086A024 /* CollectionReusableView.swift in Headers */ = {isa = PBXBuildFile; fileRef = 966ECF291CF4C20100BB0BDF /* CollectionReusableView.swift */; settings = {ATTRIBUTES = (Public, ); }; };
 		96E3C3971D3A1CC20086A024 /* Material+UIView.swift in Headers */ = {isa = PBXBuildFile; fileRef = 96E3C3931D397AE90086A024 /* Material+UIView.swift */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -295,6 +296,7 @@
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 		96D88BFD1C1328D800B91418 /* LICENSE */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = LICENSE; sourceTree = "<group>"; };
 		96D88C091C1328D800B91418 /* Material.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = Material.h; sourceTree = "<group>"; };
+		96DE566B1EF1B63B006DA70E /* PanController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PanController.swift; sourceTree = "<group>"; };
 		96E3C3931D397AE90086A024 /* Material+UIView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "Material+UIView.swift"; sourceTree = "<group>"; };
 		96F1DC871D654FDF0025F925 /* Material+CALayer.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "Material+CALayer.swift"; sourceTree = "<group>"; };
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@@ -440,6 +442,7 @@
 			children = (
 				9606CFAB1E957AC3006B4E74 /* TabsController.swift */,
 				96BCB79A1CB40DC500C806FE /* TabBar.swift */,
+				96DE566B1EF1B63B006DA70E /* PanController.swift */,
 			);
 			name = Tabs;
 			sourceTree = "<group>";
@@ -976,6 +979,7 @@
 				965E81161DD4D5C800D61E4B /* DisplayStyle.swift in Sources */,
 				965E81171DD4D5C800D61E4B /* RootController.swift in Sources */,
 				965E81181DD4D5C800D61E4B /* Snackbar.swift in Sources */,
+				96DE566C1EF1B63B006DA70E /* PanController.swift in Sources */,
 				965E81191DD4D5C800D61E4B /* SnackbarController.swift in Sources */,
 				965E811A1DD4D5C800D61E4B /* StatusBarController.swift in Sources */,
 				965E811B1DD4D5C800D61E4B /* Switch.swift in Sources */,

Sources/iOS/PanController.swift

+/*
+ * Copyright (C) 2015 - 2017, Daniel Dahan and CosmicMind, Inc. <http://cosmicmind.com>.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *	*	Redistributions of source code must retain the above copyright notice, this
+ *		list of conditions and the following disclaimer.
+ *
+ *	*	Redistributions in binary form must reproduce the above copyright notice,
+ *		this list of conditions and the following disclaimer in the documentation
+ *		and/or other materials provided with the distribution.
+ *
+ *	*	Neither the name of CosmicMind nor the names of its
+ *		contributors may be used to endorse or promote products derived from
+ *		this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import UIKit
+import Motion
+
+enum PanTransitionState {
+    case normal
+    case slidingLeft
+    case slidingRight
+}
+
+extension UIViewController {
+    /**
+     A convenience property that provides access to the PanController.
+     This is the recommended method of accessing the PanController
+     through child UIViewControllers.
+     */
+    public var panController: PanController? {
+        var viewController: UIViewController? = self
+        while nil != viewController {
+            if viewController is PanController {
+                return viewController as? PanController
+            }
+            viewController = viewController?.parent
+        }
+        return nil
+    }
+}
+
+open class PanController: UIViewController {
+    /// A reference to the pan gesture recognizer.
+    fileprivate var panGestureRecognizer: UIPanGestureRecognizer!
+    
+    /// The pan transition state.
+    fileprivate var panTransitionState: PanTransitionState = .normal
+    
+    /// A reference to the next view controller being loaded.
+    fileprivate var loadingViewController: UIViewController?
+    
+    /// A reference to the loading index within the view controllers.
+    fileprivate var loadingIndex: Int?
+    
+    /// A reference to the currently selected view controller index value.
+    @IBInspectable
+    open var selectedIndex = 0
+    
+    /// An Array of UIViewControllers.
+    open var viewControllers: [UIViewController] {
+        didSet {
+            oldValue.forEach { [weak self] in
+                self?.removeViewController(viewController: $0)
+            }
+        }
+    }
+    
+    /**
+     An initializer that initializes the object with a NSCoder object.
+     - Parameter aDecoder: A NSCoder instance.
+     */
+    public required init?(coder aDecoder: NSCoder) {
+        viewControllers = []
+        super.init(coder: aDecoder)
+    }
+    
+    /**
+     An initializer that accepts an Array of UIViewControllers.
+     - Parameter viewControllers: An Array of UIViewControllers.
+     */
+    public init(viewControllers: [UIViewController], selectedIndex: Int = 0) {
+        self.viewControllers = viewControllers
+        self.selectedIndex = selectedIndex
+        super.init(nibName: nil, bundle: nil)
+    }
+    
+    open override func viewDidLoad() {
+        super.viewDidLoad()
+        prepare()
+    }
+    
+    open override func viewWillLayoutSubviews() {
+        super.viewWillLayoutSubviews()
+        layoutSubviews()
+    }
+    
+    /**
+     To execute in the order of the layout chain, override this
+     method. `layoutSubviews` should be called immediately, unless you
+     have a certain need.
+     */
+    open func layoutSubviews() {
+    }
+    
+    /**
+     Prepares the view instance when intialized. When subclassing,
+     it is recommended to override the prepare method
+     to initialize property values and other setup operations.
+     The super.prepare method should always be called immediately
+     when subclassing.
+     */
+    open func prepare() {
+        view.contentScaleFactor = Screen.scale
+        preparePanGestureRecognizer()
+        prepareViewController(at: selectedIndex)
+    }
+}
+
+extension PanController {
+    /// Prepares the pan gesture recognizer.
+    fileprivate func preparePanGestureRecognizer() {
+        panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture))
+        view.addGestureRecognizer(panGestureRecognizer)
+    }
+    
+    /**
+     Loads a view controller based on its index in the viewControllers Array
+     and adds it as a child view controller.
+     - Parameter at index: An Int for the viewControllers index.
+     */
+    fileprivate func prepareViewController(at index: Int) {
+        let v = viewControllers[index]
+        
+        guard !childViewControllers.contains(v) else {
+            return
+        }
+        
+        addChildViewController(v)
+        view.addSubview(v.view)
+        v.didMove(toParentViewController: self)
+        v.view.frame = view.bounds
+        v.view.clipsToBounds = true
+        v.view.contentScaleFactor = Screen.scale
+    }
+}
+
+extension PanController {
+    /**
+     Removes the view controller as a child view controller with
+     the given index.
+     - Parameter at index: An Int for the view controller position.
+     */
+    fileprivate func removeViewController(at index: Int) {
+        let v = viewControllers[index]
+        
+        guard childViewControllers.contains(v) else {
+            return
+        }
+        
+        removeViewController(viewController: v)
+    }
+    
+    /**
+     Removes a given view controller from the childViewControllers array.
+     - Parameter at index: An Int for the view controller position.
+     */
+    fileprivate func removeViewController(viewController: UIViewController) {
+        viewController.willMove(toParentViewController: nil)
+        viewController.view.removeFromSuperview()
+        viewController.removeFromParentViewController()
+    }
+}
+
+extension PanController {
+    @objc
+    func handlePanGesture() {
+        let tx = panGestureRecognizer.translation(in: nil).x
+        let vx = panGestureRecognizer.velocity(in: nil).x
+        
+        switch panGestureRecognizer.state {
+        case .began, .changed:
+            let nextState: PanTransitionState
+            
+            if .normal == panTransitionState {
+                nextState = vx < 0 ? .slidingLeft : .slidingRight
+            } else {
+                nextState = tx < 0 ? .slidingLeft : .slidingRight
+            }
+            
+            if nil == loadingIndex {
+                loadingIndex = .slidingLeft == panTransitionState ? selectedIndex - 1 : selectedIndex + 1
+            }
+            
+            guard let i = loadingIndex, -1 < i && i < viewControllers.count else {
+                loadingIndex = nil
+                return
+            }
+            
+            if nextState != panTransitionState {
+                Motion.shared.cancel(isAnimated: false)
+                
+                loadingViewController = PanController(viewControllers: viewControllers, selectedIndex: i)
+                
+                panTransitionState = nextState
+                motionReplaceViewController(with: loadingViewController!)
+            } else {
+                let progress = abs(Double(tx / view.bounds.width))
+                
+                Motion.shared.update(elapsedTime: progress)
+                
+                if .slidingLeft == panTransitionState, let v = loadingViewController {
+                    Motion.shared.apply(transitions: [.translate(x: view.bounds.width + tx)], to: v.view)
+                } else {
+                    Motion.shared.apply(transitions: [.translate(x: tx)], to: view)
+                }
+            }
+        default:
+            let progress = (tx + vx) / view.bounds.width
+            
+            if (progress < 0) == (.slidingLeft == panTransitionState) && 0.3 < abs(progress) {
+                Motion.shared.end()
+            } else {
+                Motion.shared.cancel()
+            }
+            
+            panTransitionState = .normal
+            loadingViewController = nil
+            loadingIndex = nil
+        }
+    }
+}
+