Swift封装滑出式导航栏

前言：本文将会创建以下几个主类：

DWContainerViewController：这包含了左视图，中视图和右视图控制器的视图，并处理动画和滑动等操作。 DWCenterViewController：中央面板。 DWSidePanelViewController：用于左侧和右侧面板。

创建storyboard，如图：

并且创建DWCenterViewController、DWStarCell、DWSidePanelViewController，关联上图中的storyboard

DWCenterViewController为滑出式导航的类，代码：

class DWCenterViewController: UIViewController {var delegate: DWCenterViewControllerDelegate?@IBOutlet weak var imageView: UIImageView!@IBOutlet weak var titleLabel: UILabel!@IBOutlet weak var creatorLabel: UILabel!@IBAction func actorsTapped(_ sender: Any) {//左边点击事件   }
}
复制代码

DWStarCell代码：

class DWStarCell: UITableViewCell {@IBOutlet weak var animalImageView: UIView!@IBOutlet weak var imageNameLabel: UILabel!@IBOutlet weak var imageCreatorLabel: UILabel!}
复制代码

创建DWStar.swift模型，并且初始化cell显示的数据，代码如下：

//结构体
struct DWStar {let title: Stringlet creator: Stringlet image: UIImage?//重写init方法init(title: String, creator: String, image:UIImage?) {self.title = titleself.creator = creatorself.image = image}static func allActors() -> [DWStar] {return [DWStar(title: "林志玲", creator: "Dwyane", image: UIImage(named: "ID-100113060")),DWStar(title: "张歆艺", creator: "Dwyane", image: UIImage(named: "ID-10022760")),DWStar(title: "李连杰", creator: "Dwyane", image: UIImage(named: "ID-10091065")),DWStar(title: "周润发", creator: "Dwyane", image: UIImage(named: "ID-10047796")),DWStar(title: "舒淇", creator: "Dwyane", image: UIImage(named: "ID-10092572")),DWStar(title: "鹿晗", creator: "Dwyane", image: UIImage(named: "ID-10041194")),DWStar(title: "黄晓明", creator: "Dwyane", image: UIImage(named: "ID-10017782")),DWStar(title: "李赛凤", creator: "Dwyane", image: UIImage(named: "ID-10091745")),DWStar(title: "赵丽颖", creator: "Dwyane Ratcliff", image: UIImage(named: "ID-10056941")),DWStar(title: "周星驰", creator: "Dwyane", image: UIImage(named: "ID-10019208")),DWStar(title: "杜海涛", creator: "Dwyane", image: UIImage(named: "ID-10011404"))]}复制代码

创建DWCenterViewControllerDelegate，并且创建协议方法：

//创建协议 optional：类似oc的可选
@objc
protocol DWCenterViewControllerDelegate {@objc optional func toggleLeftPanel()  //切换左边的容器@objc optional func collapseSidePanels() //折叠侧边的容器
}
复制代码

在DWCenterViewController.swift的actorsTapped点击方法调用协议方法toggleLeftPanel，如下：

@IBAction func actorsTapped(_ sender: Any) {//左边点击事件delegate?.toggleLeftPanel?()
}
复制代码

创建DWSidePanelViewControllerDelegate.swift，并创一个协议

protocol DWSidePanelViewControllerDelegate {func didSelectAnimal(_ animal: DWStar)  //选择的动物
}
复制代码

在DWCenterViewController.swift实现DWSidePanelViewControllerDelegate的协议方法：

// MARK: - DWCenterViewController delegate
//在该类实现delegate的方法
extension DWCenterViewController: DWSidePanelViewControllerDelegate {func didSelectAnimal(_ animal: DWStar) { //实现协议方法imageView.image = animal.imagetitleLabel.text = animal.titlecreatorLabel.text = animal.creatordelegate?.collapseSidePanels?() //折叠侧容器}  
}
复制代码

创建DWContainerViewController.swift，并定义一些属性：

//枚举  滑动状态
enum SlideOutState {case bothCollapsed  //侧容器折叠case leftPanelExpanded   //左容器展开case rightPanelExpanded  //右容器展开
}//定义属性
var centerNavigationController: UINavigationController!
var centerViewController: DWCenterViewController!
//当前状态
var currentState: SlideOutState = .bothCollapsed {didSet { //在属性值改变后触发didSetlet shoulShowShadow = currentState != .bothCollapsed}
}var leftViewController: DWSidePanelViewController?
var centerPanelExpandedOffset: CGFloat = 60 //该值是中央视图控制器在屏幕外动画显示后左侧可见的宽度（以点为单位）
复制代码

扩展UIStoryboard,方便取得VC,代码如下：

private extension UIStoryboard {static func mainStoryboard() -> UIStoryboard {return UIStoryboard(name: "Main", bundle: Bundle.main)}static func centerViewController() -> DWCenterViewController? {return mainStoryboard().instantiateViewController(withIdentifier: "DWCenterViewController") as? DWCenterViewController}static func leftViewController() -> DWSidePanelViewController? {return mainStoryboard().instantiateViewController(withIdentifier: "LeftViewController") as? DWSidePanelViewController}    
}
复制代码

在viewDidLoad添加如下：

//添加中间控制器并显示
centerViewController = UIStoryboard.centerViewController()
centerViewController.delegate = self//将centerViewController包装在导航控制器中
centerNavigationController = UINavigationController(rootViewController: centerViewController)
//加入centerViewcontroller的视图
view.addSubview(centerNavigationController.view)
//加入centerViewcontroller的视图控制器
addChildViewController(centerNavigationController)
centerNavigationController.didMove(toParentViewController: self)
复制代码

实现协议方法（添加左侧容器一起动画的发生代码）：

extension DWContainerViewController: DWCenterViewControllerDelegate { 
}
复制代码

在协议方法中，添加

func toggleLeftPanel() {//如果当前状态：左边为展开let notAlreadyExpanded = (currentState != .leftPanelExpanded)if notAlreadyExpanded {addLeftPanelViewController() //添加左边容器}//左边容器展开的动画animateLeftPanel(shouldExpand: notAlreadyExpanded)
}//折叠侧边容器
func collapseSidePanels() {switch currentState {case .leftPanelExpanded:toggleLeftPanel()default:break}
}//左边的VC
func addLeftPanelViewController() {//guard语句判断其后的表达式布尔值为false时，才会执行之后代码块里的代码，如果为true，则跳过整个guard语句guard leftViewController == nil else { return }if let vc = UIStoryboard.leftViewController() {vc.animals = DWStar.allActors()addChildSidePanelController(vc)leftViewController = vc}
}func addChildSidePanelController(_ sidePanelController: DWSidePanelViewController) {sidePanelController.delegate = centerViewControllerview.insertSubview(sidePanelController.view, at: 0)addChildViewController(sidePanelController)sidePanelController.didMove(toParentViewController: self)
}//右边的VC
func addRightPanelViewController() {}func animateLeftPanel(shouldExpand: Bool) {if shouldExpand {currentState = .leftPanelExpandedanimateCenterPanelXPosition(targetPosition: centerNavigationController.view.frame.width - centerPanelExpandedOffset)} else {animateCenterPanelXPosition(targetPosition: 0, completion: { (_) inself.currentState = .bothCollapsedself.leftViewController?.view.removeFromSuperview()self.leftViewController = nil})}
}//检查是否被告知展开或折叠侧面板。如果它应该展开，那么它将设置当前状态以指示左侧面板展开，然后为中央面板设置动画，以便打开。否则，它将关闭中央面板，然后移除其视图，并设置当前状态以指示其关闭。
func animateCenterPanelXPosition(targetPosition: CGFloat, completion: ((Bool) -> Void)? = nil) {UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.8, initialSpringVelocity: 0, options: .curveEaseOut, animations: {self.centerNavigationController.view.frame.origin.x = targetPosition}, completion: completion)
}func showShadowForCenterViewController(_ shouldShowShadow: Bool) {if shouldShowShadow {centerNavigationController.view.layer.shadowOpacity = 0.8} else {centerNavigationController.view.layer.shadowOpacity = 0.0}
}}
复制代码

添加手势，更改DWCenterViewController的导航栏x坐标

// 手势
// MARK: Gesture recognizer
extension DWContainerViewController: UIGestureRecognizerDelegate {@objc func handlePanGesture(_ recognize: UIPanGestureRecognizer) {let gestureIsDraggingFromLeftToRight = (recognize.velocity(in: view).x > 0)switch recognize.state {case .began:if currentState == .bothCollapsed {if gestureIsDraggingFromLeftToRight {//左边addLeftPanelViewController()} else {//右边addRightPanelViewController()}showShadowForCenterViewController(true)}case .changed:if let rview = recognize.view {rview.center.x = rview.center.x + recognize.translation(in: view).xrecognize.setTranslation(CGPoint.zero, in: view)//translationInView:方法获取View的偏移量  setTranslation:方法设置手势的偏移量}case .ended: //根据不同的方向移动左或右if let _ = leftViewController,let rview = recognize.view {let hasMovedGreaterThanHalfway = rview.center.x > view.bounds.size.widthanimateLeftPanel(shouldExpand: hasMovedGreaterThanHalfway)}default:break}}
}
复制代码