我一直在努力创建一个UIAlertView在Swift，但由于某种原因，我不能得到正确的声明，因为我得到这个错误:
无法找到一个超载的'init'接受提供的 参数
我是这样写的:
let button2Alert: UIAlertView = UIAlertView(title: "Title", message: "message",
delegate: self, cancelButtonTitle: "OK", otherButtonTitles: nil)
然后我使用:
button2Alert.show()
到目前为止，它正在崩溃，我只是不能得到正确的语法。
当前回答
斯威夫特有一个有趣的例子:
private func presentRandomJoke() {
if let randomJoke: String = jokesController.randomJoke() {
let alertController: UIAlertController = UIAlertController(title:nil, message:randomJoke, preferredStyle: UIAlertControllerStyle.Alert)
alertController.addAction(UIAlertAction(title:"Done", style:UIAlertActionStyle.Default, handler:nil))
presentViewController(alertController, animated:true, completion:nil)
}
}
其他回答
在xcode 9中
let alert = UIAlertController(title: "Alert", message: "message", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
如果你的目标是iOS 7和8，你需要这样的东西来确保你对每个版本都使用了正确的方法，因为UIAlertView在iOS 8中已弃用，但UIAlertController在iOS 7中不可用:
func alert(title: String, message: String) {
if let getModernAlert: AnyClass = NSClassFromString("UIAlertController") { // iOS 8
let myAlert: UIAlertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)
myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
self.presentViewController(myAlert, animated: true, completion: nil)
} else { // iOS 7
let alert: UIAlertView = UIAlertView()
alert.delegate = self
alert.title = title
alert.message = message
alert.addButtonWithTitle("OK")
alert.show()
}
}
通过Swift 2的协议扩展，你可以创建一个为视图控制器提供默认实现的协议:
ShowsAlert.swift
import UIKit
protocol ShowsAlert {}
extension ShowsAlert where Self: UIViewController {
func showAlert(title: String = "Error", message: String) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)
alertController.addAction(UIAlertAction(title: "Ok", style: .Default, handler: nil))
presentViewController(alertController, animated: true, completion: nil)
}
}
ViewController.swift
class ViewController: UIViewController, ShowsAlert {
override func viewDidLoad() {
super.viewDidLoad()
showAlert(message: "Hey there, I am an error message!")
}
}
AlertView Swift 5及以上:-
let alert = UIAlertController(title: LocalizedStringConstant.alert, message: message, preferredStyle: UIAlertController.Style.alert)
alert.addAction(UIAlertAction(title: "Retry", style: .cancel, handler: { (_) in
}))
self.present(alert, animated: true, completion: nil)
或者这样做
let alert = UIAlertController(title: "Alert", message: "Saved Successfully", preferredStyle: UIAlertController.Style.alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertAction.Style.default, handler: nil))
self.present(alert, animated: true, completion: nil)
