小编Mik*_*ike的帖子

@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做+ ="(x)"

错误:二元运算符'+ ='不能应用于'String？'类型的操作数 和'字符串'

我希望每次用户选择"是"时它增加1.现在显然它只停留在1.