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
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!")
}
}
其他回答
它不工作的原因是因为你传递给函数的某个值不正确。swift不像Objective-C，你可以把nil放在类类型的参数中，没有任何限制(可能是)。参数otherButtonTitles被定义为非可选的，其类型的末尾没有(?)。所以你必须传递一个具体的值给它。
SWIFT 4:简单地为UIViewController创建一个扩展，如下所示:
extension UIViewController {
func showSuccessAlert(withTitle title: String, andMessage message:String) {
let alert = UIAlertController(title: title, message: message,
preferredStyle: UIAlertController.Style.alert)
alert.addAction(UIAlertAction(title: "OK".localized, style:
UIAlertAction.Style.default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
}
现在在你的ViewController中，直接调用上面的函数，就好像它们是由UIViewController提供的一样。
yourViewController.showSuccessAlert(withTitle:
"YourTitle", andMessage: "YourCustomTitle")
显示UIAlertView在swift语言:-
Protocol UIAlertViewDelegate
let alert = UIAlertView(title: "alertView", message: "This is alertView", delegate:self, cancelButtonTitle:"Cancel", otherButtonTitles: "Done", "Delete")
alert.show()
显示UIAlertViewController在swift语言:-
let alert = UIAlertController(title: "Error", message: "Enter data in Text fields", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alert, animated: true, completion: nil)
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!")
}
}
class Preview: UIViewController , UIAlertViewDelegate
{
@IBAction func MoreBtnClicked(sender: AnyObject)
{
var moreAlert=UIAlertView(title: "Photo", message: "", delegate: self, cancelButtonTitle: "No Thanks!", otherButtonTitles: "Save Image", "Email", "Facebook", "Whatsapp" )
moreAlert.show()
moreAlert.tag=111;
}
func alertView(alertView: UIAlertView, didDismissWithButtonIndex buttonIndex: Int)
{
if alertView.tag==111
{
if buttonIndex==0
{
println("No Thanks!")
}
else if buttonIndex==1
{
println("Save Image")
}
else if buttonIndex == 2
{
println("Email")
}
else if buttonIndex == 3
{
println("Facebook")
}
else if buttonIndex == 4
{
println("Whatsapp")
}
}
}
}
