ios - 快速传递带参数的闭包作为参数

Question

所以我们的想法是创建一个通用警报创建器，我可以将完成处理程序传递给......

 static func makeTextFieldAlert(msg:String, title:String, onOk: @escaping (_ newText:String) -> Void ) -> UIAlertController {
        let alertController = UIAlertController(title: "Add New Name", message: "", preferredStyle: UIAlertController.Style.alert)

        let saveAction = UIAlertAction(title: "Save", style: UIAlertAction.Style.default, handler: { alert -> Void in
            let firstTextField = alertController.textFields![0] as UITextField
            onOk(firstTextField.text!)
        })

但是......xcode强制我把_放在那里，它强制我把@escaping放在那里......

而且......当我尝试调用这整个困惑......它甚至不会编译:

@IBAction func click(_ sender: Any) {
        print("here")
        let newThing:UIAlertController = Util.makeTextFieldAlert(msg: "Yes", title: "Create Thing", onOk:{_ in
            ThingUtil.createThing(thing: newText)
        } )

所以我尝试用 $0 代替 newText 并得到

"Anonymous closure arguments cannot be used inside a closure that has explicit arguments"

我尝试了上面的方法，得到了:

Use of unresolved identifier 'newText'

为了清楚起见，我宁愿只使用变量 newText......但此时，我只想编译它。我究竟做错了什么？谢谢!

Answer 1

这个“东西”正在我的最后编译:

class Util {
    static func makeTextFieldAlert(msg:String, title:String, onOk: @escaping (_ newText:String) -> Void ) -> UIAlertController {
        let alertController = UIAlertController(title: "Add New Name", message: "", preferredStyle: UIAlertController.Style.alert)

        let saveAction = UIAlertAction(title: "Save", style: UIAlertAction.Style.default, handler: { alert -> Void in
            let firstTextField = alertController.textFields![0] as UITextField
            onOk(firstTextField.text!)
        })
        alertController.addAction(saveAction)
        return alertController
    }
}


class ViewController: UIViewController {


    @IBAction func click(_ sender: Any) {
        print("here")
        let newThing:UIAlertController = Util.makeTextFieldAlert(msg: "Yes", title: "Create Thing", onOk:{ newText in
            print(newText)
        } )
        present(newThing, animated: true, completion: nil)
    }

}

问题可能出在 ThingUtil.createThing(thing: newText) 上。您确定它需要一个字符串参数吗？

这应该是您的 ThingUtil 类 API

class ThingUtil {
    static func createThing(thing:String) {

    }
}