swift - 显示 Swift 4 错误警报

Question

以下代码在调用 .present 时给我一个 sigabort:

    func alert(message: String, title: String = "") {

        let alertController =  UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
        alertController.addAction(UIAlertAction(title: "Ok", style: .default, handler: { action in
            switch action.style {
                case .default:
                    print("default")
                case .cancel:
                    print("cancel")
                case .destructive:
                    print("destructive")
            }}))
        alertController.present(alertController, animated: true, completion: nil)
    }

救命啊!我不明白这个!

Answer 1

您正在调用alertController 的present，而不是 View 的present。将其更改为引用父 UIViewController 的present(...)。

func present(_ viewControllerToPresent: UIViewController, 
    animated flag: Bool, 
  completion: (() -> Void)? = nil)

https://developer.apple.com/documentation/uikit/uiviewcontroller/1621380-present