ios - present(_:animated:completion :)在Swift 3中不起作用

Question

因此，当我尝试在Swift中使用present()函数时，它总是崩溃。这是我的代码

func infoOpener(sender: UISwipeGestureRecognizer) {

    let location: CGPoint = sender.location(in: tableView)

    let cellPath: IndexPath = tableView.indexPathForRow(at: location)!


    let VC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "userInfo") as! userInfoVC

    VC.username = "@\(self.user[cellPath.row].username)"
    VC.imageUrl = self.user[cellPath.row].imagePath


    self.present(VC, animated: false, completion: nil)

}

每当我使用present(_:animated:completion:)函数时，都会出现EXC_BREAKPOINT错误。有人可以帮我吗？

Answer 1

使用if let或guard let代替用!强制展开Optionals可以使您的代码更健壮:

func infoOpener(sender: UISwipeGestureRecognizer) {

    let location: CGPoint = sender.location(in: tableView)

    guard let cellPath: IndexPath = tableView.indexPathForRow(at: location) else {
       print("No index path found")
       return
    }

    guard let VC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "userInfo") as? userInfoVC else {
        print("View controller could not be instantiated")
        return
    }

    VC.username = "@\(self.user[cellPath.row].username)"
    VC.imageUrl = self.user[cellPath.row].imagePath


    self.present(VC, animated: false, completion: nil)

}