如何实现系统的全屏返回手势

实现返回手势有两种比较简单的方式:

• 1. 利用系统的边缘侧滑返回手势
• 2. 给导航控制器加一个UIPanGestureRecognizer，利用系统的返回Selector(("handleNavigationTransition:"))实现全屏左滑返回

我们这里给UINavigationController实现了一个分类，代码如下:

import UIKit

// MARK: - 添加全屏返回手势
extension UINavigationController: UIGestureRecognizerDelegate {
    
    /// 添加边缘返回
    func addEdgeScreenPopGesture(){
        self.interactivePopGestureRecognizer?.delegate = self
    }
    
    /// 添加全屏返回
    func addFullScreenPopGesture(){
        let panges = UIPanGestureRecognizer(target: self.interactivePopGestureRecognizer?.delegate, action: Selector(("handleNavigationTransition:")));
        panges.delegate = self;
        self.view.addGestureRecognizer(panges);
    }
    
    // MARK: - UIGestureRecognizerDelegate

    // 单个页面控制是否失效
    public func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
        if (self.childViewControllers.count > 1 && (self.interactivePopGestureRecognizer?.isEnabled)!) {
            return true;
        } else {
            return false;
        }
    }
    
    /// 解决scrollView横向滑动手势覆盖屏幕边缘侧滑手势,返回无响应问题(需要在冲突的scrollView控制器中调用)
    ///
    /// - Parameter scrollView: 手势冲突的scrollView
    func handleEdgePopGestureConflict(scrollView: UIScrollView) {
        if let edgePan = self.getScreenEdgePanGestureRecognizer() {
            scrollView.panGestureRecognizer.require(toFail: edgePan)
        }
    }
    
    /// 越级pop(点击返回按钮或边缘返回时跨级,A push B push C,  C pop A, B push C时调用此方法,popStep为2)
    ///
    /// - Parameters:
    ///   - viewController: viewController
    ///   - popStep: 点击返回按钮或边缘返回时跨级步数
    func pushViewController(_ viewController: UIViewController, popStep: Int) {
        viewController.hidesBottomBarWhenPushed = true
        self.pushViewController(viewController, animated: true)
        let endIndex = self.viewControllers.count - 1
        let beginIndex = endIndex - popStep + 1
        self.viewControllers.removeSubrange(beginIndex ..< endIndex)
    }
    
    // MARK: - private
    
    /// 获取屏幕边缘侧滑手势
    fileprivate func getScreenEdgePanGestureRecognizer() -> UIScreenEdgePanGestureRecognizer? {
        var edgePan: UIScreenEdgePanGestureRecognizer?
        if let recognizers = view.gestureRecognizers, recognizers.count > 0 {
            for recognizer in recognizers {
                if recognizer is UIScreenEdgePanGestureRecognizer {
                    edgePan = recognizer as? UIScreenEdgePanGestureRecognizer
                    break
                }
            }
        }
        return edgePan
    }
    
    // MARK: - 特殊情况用法
    
    /// 当点击返回按钮(侧滑返回)需要做相关处理,则在这个特殊的控制器中添加此方法处理
//    override func willMove(toParentViewController parent: UIViewController?) {
//        if parent == nil {
//            print("当点击返回按钮需要弹框确定后在返回,在这个特殊的控制器中添加此方法处理")
//        }
//    }
}

问题1： 当遇到横向滚动的scrollView时不响应侧滑返回

• 需要在scrollView控制器中调用handleEdgePopGestureConflict
• 或者通过函数

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {   
 }

控制,给导航控制器关联一个是否模糊响应的变量（如isSimultaneouslyGesture）,通过具体的控制器来设置是否模糊响应

问题2：越级pop，点击返回按钮或边缘返回时跨级

• 如A push B push C, C pop A, B push C时调用此方法,popStep为2(在B push C时移除导航控制器的中间部分的子控制器viewControllers)