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
Swift 5上的SwiftUI。x和Xcode 11.x
import SwiftUI
struct ContentView: View {
@State private var isShowingAlert = false
var body: some View {
VStack {
Button("A Button") {
self.isShowingAlert.toggle()
}
.alert(isPresented: $isShowingAlert) { () -> Alert in
Alert(
title: Text("Alert"),
message: Text("This is an alert"),
dismissButton:
.default(
Text("OK"),
action: {
print("Dismissing alert")
}
)
)
}
}
.padding()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
其他回答
你可以使用这个简单的扩展与n个按钮和相关的动作swift4以上
extension UIViewController {
func popupAlert(title: String?, message: String?, actionTitles:[String?], actions:[((UIAlertAction) -> Void)?]) {
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
for (index, title) in actionTitles.enumerated() {
let action = UIAlertAction(title: title, style: .default, handler: actions[index])
alert.addAction(action)
}
self.present(alert, animated: true, completion: nil)
}
}
你可以这样使用它，
self.popupAlert(title: "Message", message: "your message", actionTitles: ["first","second","third"], actions:[
{action1 in
//action for first btn click
},
{action2 in
//action for second btn click
},
{action3 in
//action for third btn click
}, nil])
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)
从UIAlertView类:
// UIAlertView已弃用。使用UIAlertController 将UIAlertControllerStyleAlert改为preferredStyle
在iOS 8上，你可以这样做:
let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alert, animated: true, completion: nil)
UIAlertController是一个单独的类，用于创建和交互我们在ios8中知道的UIAlertViews和UIActionSheets。
编辑:处理动作:
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { action in
switch action.style{
case .Default:
print("default")
case .Cancel:
print("cancel")
case .Destructive:
print("destructive")
}
}}))
为Swift 3编辑:
let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
为Swift 4.x编辑:
let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { action in
switch action.style{
case .default:
print("default")
case .cancel:
print("cancel")
case .destructive:
print("destructive")
}
}))
self.present(alert, animated: true, completion: nil)
在IOS 9上，你可以这样做
let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
Swift 5上的SwiftUI。x和Xcode 11.x
import SwiftUI
struct ContentView: View {
@State private var isShowingAlert = false
var body: some View {
VStack {
Button("A Button") {
self.isShowingAlert.toggle()
}
.alert(isPresented: $isShowingAlert) { () -> Alert in
Alert(
title: Text("Alert"),
message: Text("This is an alert"),
dismissButton:
.default(
Text("OK"),
action: {
print("Dismissing alert")
}
)
)
}
}
.padding()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
