UINavigationController 返回手势与 leftBarButtonItem

UINavigationController 返回手势与 leftBarButtonItem

UINavigationController 自带从屏幕左侧边缘向右滑动的返回手势,可以通过这个手势实现 pop,或者 pop 中途取消 pop 而停留在当前控制器(UIViewController)。如果设置了当前控制器的 navigationItem.leftBarButtonItem 或 navigationItem.leftBarButtonItems,则返回手势失效。可以通过自定义 NavigationController,实现设置 navigationItem.leftBarButtonItem 或 navigationItem.leftBarButtonItems,并且保留返回手势。代码已上传 GitHub:https://github.com/Silence-GitHub/NavigationControllerDemo

UINavigationController 的 interactivePopGestureRecognizer 属性为返回手势。设置手势的 delegate,手动管理返回手势。当 UINavigationController 没有或只有一个子控制器时,返回手势不能响应,否则会出现奇怪的现象。自定义 currentNotRootVC 属性,记录当前的非根子控制器(只有一个子控制器时,此子控制器为根子控制器,root view controller)。设置 UINavigationController 的 delegate,通过 UINavigationControllerDelegate 的方法,更新 currentNotRootVC。代码示例如下

import UIKit

class NavigationController: UINavigationController, UINavigationControllerDelegate, UIGestureRecognizerDelegate {

	// Current child view controller, but not root view controller
    private var currentNotRootVC: UIViewController?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        delegate = self
        interactivePopGestureRecognizer?.delegate = self
    }
    
    // MARK: - UINavigationControllerDelegate
    
    func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
        currentNotRootVC = viewControllers.count <= 1 ? nil : viewController
        /*
        switch viewController {
        case is SomeVCClassForbidPopGesture:
            interactivePopGestureRecognizer?.isEnabled = false
        default:
            interactivePopGestureRecognizer?.isEnabled = true
        }
         */
    }
    
    // MARK: - UIGestureRecognizerDelegate
    
    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        if interactivePopGestureRecognizer == gestureRecognizer {
        	// Begin to pop only when top view controller is current child view controller but not root view controller
            return currentNotRootVC == topViewController
        }
        return true
    }

}

如果有部分控制器不允许返回手势(例如编辑信息,退出页面需要确认),则在func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool)方法中,加入对 viewController 的判断,开启或禁用返回手势。

参考:http://www.cnblogs.com/v2m_/p/3521569.html

转载请注明出处:http://www.cnblogs.com/silence-cnblogs/p/6618056.html

posted on 2017-03-25 19:16  Silence_cnblogs  阅读(999)  评论(0编辑  收藏  举报