UITabBarController 使用方法示例

学习教程，看到这样设计 UITabBarController，感觉很不错。好记性不如烂笔头，记录一下：

 let tabBarDelegate = TabBarDelegate()

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        
        let tabController = UITabBarController()
        
        let homeStoryboard = UIStoryboard(name: "Home", bundle: nil)
        
        let searchStoryboard = UIStoryboard(name: "Search", bundle: nil)
        
        let newPostStoryboard = UIStoryboard(name: "NewPost", bundle: nil)
        
        let profileStoryboard = UIStoryboard(name: "Profile", bundle: nil)
        
        let activityStoryboard = UIStoryboard(name: "Activity", bundle: nil)
        
        let homeVC = homeStoryboard.instantiateViewController(withIdentifier: "Home") as! HomeViewController
        
        let profileVC = profileStoryboard.instantiateViewController(withIdentifier: "Profile") as! ProfileViewController
        
        let searchVC = searchStoryboard.instantiateViewController(withIdentifier: "Search") as! SearchViewController
        
        let newPostVC = newPostStoryboard.instantiateViewController(withIdentifier: "NewPost") as! NewPostViewController
        
        let activityVC = activityStoryboard.instantiateViewController(withIdentifier: "Activity") as! ActivityViewController
        
        let vcData: [(UIViewController, UIImage, UIImage)] = [
        
            (homeVC, UIImage(named: "home_tab_icon")!, UIImage(named: "home_selected_tab_icon")!),
            
            (searchVC, UIImage(named: "search_tab_icon")!, UIImage(named: "search_selected_tab_icon")!),
            
            (newPostVC, UIImage(named: "post_tab_icon")!, UIImage(named: "post_tab_icon")!),
            
            (activityVC, UIImage(named: "activity_tab_icon")!, UIImage(named: "activity_selected_tab_icon")!),
            
            (profileVC, UIImage(named: "profile_tab_icon")!, UIImage(named: "profile_selected_tab_icon")!)
        
        ]
        
        let vcs = vcData.map { (vc, defaultImage, selectedImage) -> UINavigationController in
            
            let nav = UINavigationController(rootViewController: vc)
            
            nav.tabBarItem.image = defaultImage
            
            nav.tabBarItem.selectedImage = selectedImage
            
            return nav
            
        }
        
        tabController.viewControllers = vcs
        
        tabController.tabBar.isTranslucent = false
        
        tabController.delegate = tabBarDelegate
        
        if let items = tabController.tabBar.items {
            
            for item in items {
                
                if let image = item.image {
                    
                    item.image = image.withRenderingMode(UIImage.RenderingMode.alwaysOriginal)
                    
                }
                
                if let selectedImage = item.selectedImage {
                    
                    item.selectedImage = selectedImage.withRenderingMode(UIImage.RenderingMode.alwaysOriginal)
                    
                }
                
                item.imageInsets = UIEdgeInsets(top: 6, left: 0, bottom: -6, right: 0)
                
            }
            
        }
        
        UINavigationBar.appearance().backgroundColor = UIColor.white
        
        window?.rootViewController = tabController
        
        return true
    }

TabBarDelegate.swift:

import Foundation

import UIKit

class TabBarDelegate: NSObject, UITabBarControllerDelegate {
    
    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        
        let navigationController = viewController as? UINavigationController
        
        _ = navigationController?.popViewController(animated: false)
        
    }
    
    func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
        
        let selectedViewController = tabBarController.selectedViewController
        
        guard let _selectedViewController = selectedViewController else {
            
            return false
            
        }
        
        if viewController == _selectedViewController {
            
            return false
            
        }
        
        guard let controllerIndex = tabBarController.viewControllers?.index(of: viewController) else {
            
            return true
            
        }
        
        if controllerIndex == 2 {
            
            let newPostStoryboard = UIStoryboard(name: "NewPost", bundle: nil)
            
            let newPostVC = newPostStoryboard.instantiateViewController(withIdentifier: "NewPost") as! NewPostViewController
            
            let navController = UINavigationController(rootViewController: newPostVC)
            
            _selectedViewController.present(navController, animated: true, completion: nil)
            
            return false
            
        }
        
        let navigationController = viewController as? UINavigationController
        
        _ = navigationController?.popToRootViewController(animated: false)
        
        return true
        
    }
    
    
}