如何在应用程序加载过程中更新徽章值

Question

在我的应用程序中，我需要根据购物车项目数量显示徽章值，并且我在视图控制器中实现了以下行，我使用JSON和徽章值来获得数据每当显示视图控制器时都不会加载，并且在删除后不更新值，并且徽章值在应用程序开始时没有显示，因为我是Swift 3的新手，我不在哪里实施，任何人都可以帮助我如何清除问题 ？

let appDelegate = UIApplication.shared.delegate as! AppDelegate
 func downloadJsonWithURL() {
        let url = NSURL(string: urlString)
        URLSession.shared.dataTask(with: (url as URL?)!, completionHandler: {(data, response, error) -> Void in
            if let jsonObj = try? JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? NSDictionary {
                //  print(jsonObj!.value(forKey: "Detail"))
            self.itemsArray = (jsonObj!.value(forKey: "Detail") as? [[String: AnyObject]])!
                print(self.itemsArray.count)
                OperationQueue.main.addOperation({
                    self.tableDetails.reloadData()
                    let key = "productPrice"
                    for array in self.itemsArray{
                        if let value = array[key] {
                            let cart = String(describing: value)
                            let endIndex = cart.index(cart.endIndex, offsetBy: -2)
                            let truncated = cart.substring(to: endIndex)
                            self.totalcartPrice.append(truncated)
                            print(self.totalcartPrice)
                            var sum = 0.00
                            for numbers in self.totalcartPrice{
                                sum += Double(numbers)!
                            }
                            print(sum)
                            self.increment = Int(sum)
                            self.total = String(sum) + "0KD"
                            let tabItems = self.tabBarController?.tabBar.items as NSArray!
                            let tabItem = tabItems?[1] as! UITabBarItem
                            self.appDelegate.badgeValue = String(Int(self.itemsArray.count))
                        }
                    }
                })
            }
        }).resume()
    }
func deleteButtonAction(button : UIButton) {
        let buttonPosition = button.convert(CGPoint(), to: tableDetails)
        let index = tableDetails.indexPathForRow(at: buttonPosition)
        self.itemsArray.remove(at: (index?.row)!)
        self.tableDetails.deleteRows(at: [index!], with: .automatic)
        tableDetails.reloadData()
        let tabItems = self.tabBarController?.tabBar.items as NSArray!
        let tabItem = tabItems?[1] as! UITabBarItem
        self.appDelegate.badgeValue = String(Int(self.itemsArray.count))
        if (tableView(tableDetails, numberOfRowsInSection: 0) == 0){
            tableDetails.isHidden = true
            emptyView.isHidden = false
        }
    }

Answer 1

您需要让rootviewController从AppDelegate更新徽章。像这样

let rootViewController = self.window?.rootViewController as!UITabBarController! 
let tabArray = rootViewController?.tabBar.items as NSArray! 
let tabItem = tabArray.objectAtIndex(1) as! UITabBarItem 
tabItem.badgeValue = "34"