带UIAlertAction的增量标签栏标记是否快捷？

Question

@IBAction func addToCart(sender: AnyObject) {
    let itemObjectTitle = itemObject.valueForKey("itemDescription") as! String
    let alertController = UIAlertController(title: "Add \(itemObjectTitle) to cart?", message: "", preferredStyle: .Alert)
    let yesAction = UIAlertAction(title: "Yes", style: UIAlertActionStyle.Default) { (action) in
    var tabArray = self.tabBarController?.tabBar.items as NSArray!
    var tabItem = tabArray.objectAtIndex(1) as! UITabBarItem
    let badgeValue = "1"
    if let x = badgeValue.toInt() {
        tabItem.badgeValue = "\(x)"
    }
}

我不知道为什么我不能只做+ =“（x）”

错误：二进制运算符’+ =’无法应用于类型为’String？’的操作数 和“字符串”

我希望它在用户每次选择“是”时增加1。现在，显然它只是停留在1。

Answer 1

您可以尝试访问badgeValue并将其转换为Integer，如下所示：

迅捷2

if let badgeValue = tabBarController?.tabBar.items?[1].badgeValue,
    nextValue = Int(badgeValue)?.successor() {
    tabBarController?.tabBar.items?[1].badgeValue = String(nextValue)
} else {
    tabBarController?.tabBar.items?[1].badgeValue = "1"
}

Swift 3或更高版本

    if let badgeValue = tabBarController?.tabBar.items?[1].badgeValue,
        let value = Int(badgeValue) {
        tabBarController?.tabBar.items?[1].badgeValue = String(value + 1)
    } else {
        tabBarController?.tabBar.items?[1].badgeValue = "1"
    }

要删除徽章，只需将nil分配给重写viewDidAppear方法的badgeValue：

override func viewDidAppear(animated: Bool) {
    tabBarController?.tabBar.items?[1].badgeValue = nil
}