自 iOS8 起,苹果就建议告警框使用 UIAlertController 来代替 UIAlertView 和 UIActionSheel。
1,简单的应用(同时按钮响应Handler使用闭包函数)
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidAppear(_ animated: Bool){
super.viewDidAppear(animated)
let alertController = UIAlertController(title: "系统提示",
message: "您确定要开始学习吗?", preferredStyle: .alert)
let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
let okAction = UIAlertAction(title: "好的", style: .default, handler: {
action in
print("点击了确定")
})
alertController.addAction(cancelAction)
alertController.addAction(okAction)
self.present(alertController, animated: true, completion: nil)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
2,除了弹出,还可以使用从底部向上滑出的样式
(注意:如果上拉菜单中有“取消”按钮的话,那么它永远都会出现在菜单的底部,不管添加的次序是如何)
let alertController = UIAlertController(title: "保存或删除数据", message: "删除数据将不可恢复",
preferredStyle: .actionSheet)
let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
let deleteAction = UIAlertAction(title: "删除", style: .destructive, handler: nil)
let archiveAction = UIAlertAction(title: "保存", style: .default, handler: nil)
alertController.addAction(cancelAction)
alertController.addAction(deleteAction)
alertController.addAction(archiveAction)
self.present(alertController, animated: true, completion: nil)
3,按钮使用“告警”样式(文字颜色变红,用来来警示用户)
let okAction = UIAlertAction(title: "好的", style: .destructive, handler: nil)
4,添加任意数量文本输入框(比如可以用来实现个登陆框)
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidAppear(_ animated: Bool){
super.viewDidAppear(animated)
let alertController = UIAlertController(title: "系统登录",
message: "请输入用户名和密码", preferredStyle: .alert)
alertController.addTextField {
(textField: UITextField!) -> Void in
textField.placeholder = "用户名"
}
alertController.addTextField {
(textField: UITextField!) -> Void in
textField.placeholder = "密码"
textField.isSecureTextEntry = true
}
let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
let okAction = UIAlertAction(title: "好的", style: .default, handler: {
action in
//也可以用下标的形式获取textField let login = alertController.textFields![0]
let login = alertController.textFields!.first!
let password = alertController.textFields!.last!
print("用户名:\(login.text) 密码:\(password.text)")
})
alertController.addAction(cancelAction)
alertController.addAction(okAction)
self.present(alertController, animated: true, completion: nil)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
5,使用代码移除提示框
self.presentedViewController?.dismiss(animated: false, completion: nil)
6,提示框弹出后,过段时间自动移除
下面样例弹出一个不带按钮的消息提示框,过个两秒钟提示框自动消失。
let alertController = UIAlertController(title: "保存成功!",
message: nil, preferredStyle: .alert)
//显示提示框
self.present(alertController, animated: true, completion: nil)
//两秒钟后自动消失
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 2) {
self.presentedViewController?.dismiss(animated: false, completion: nil)
}
附:扩展 UIAlertController 方便使用
从上面的样例可以发现,每次要弹出提示框都要创建一个 UIAlertController,然后添加 action 按钮,最后再通过对应的视图控制器 present 出来。我们可以对 UIAlertController 进行个扩展,把这些操作做个封装,方便使用。
1,UIAlertController扩展(UIAlertExtension.swift)
这里增加两种提示框效果:普通消息提示框、确认提示框。并且每个提示框都可以指定显示的 VC(不指定的话则为根 VC)
import UIKit
extension UIAlertController {
//在指定视图控制器上弹出普通消息提示框
static func showAlert(message: String, in viewController: UIViewController) {
let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "确定", style: .cancel))
viewController.present(alert, animated: true)
}
//在根视图控制器上弹出普通消息提示框
static func showAlert(message: String) {
if let vc = UIApplication.shared.keyWindow?.rootViewController {
showAlert(message: message, in: vc)
}
}
//在指定视图控制器上弹出确认框
static func showConfirm(message: String, in viewController: UIViewController,
confirm: ((UIAlertAction)->Void)?) {
let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "取消", style: .cancel))
alert.addAction(UIAlertAction(title: "确定", style: .default, handler: confirm))
viewController.present(alert, animated: true)
}
//在根视图控制器上弹出确认框
static func showConfirm(message: String, confirm: ((UIAlertAction)->Void)?) {
if let vc = UIApplication.shared.keyWindow?.rootViewController {
showConfirm(message: message, in: vc, confirm: confirm)
}
}
}
2,使用样例
下面分别调用两种提示框:
//弹出普通消息提示框
UIAlertController.showAlert(message: "保存成功!")
//弹出确认选择提示框
UIAlertController.showConfirm(message: "是否提交?") { (_) in
print("点击了确认按钮!")
}