DAY 10 『 UIAlertController 』Part1

从中间弹出的 Alert
style: .default => 按钮字体颜色为预设的蓝色
handler: nil => 按下後不触发任何事

let alertController = UIAlertController(title: "alert title", message: "alert message", preferredStyle: .alert)

let alertAction = UIAlertAction(title: "OK", style: .default, handler: nil)

alertController.addAction(alertAction)
        
present(alertController, animated: true, completion: nil)

style: .destructive => 按钮字体颜色为红色
handler: { action in } => 按下後触发 action in 之後的事

let alertController = UIAlertController(title: "alert title", message: "alert message", preferredStyle: .alert)
alertController.addAction(UIAlertAction(title: "OK", style: .destructive, handler: { action in
    //按下OK後会做的事情
    print("您按下OK")
}))
present(alertController, animated: true, completion: nil)

由下而上弹出的 alert

按了"确认"的按钮後，执行print ( phone as Any, password as Any )

let controller = UIAlertController(title: "选单", message: "请问你的年纪?", preferredStyle: .actionSheet)
let ages = ["0 - 19", "20 - 39", "40 - 59", "60 - 79", "80 - 99", "100 - 100以上"]
for age in ages {
    let action = UIAlertAction(title: age, style: .default) { action in        
        print(action.title as Any) // print 出按下的按钮名称
    }
    // 有几个 ages 就有几个按钮。当选项太多时， UIAlertController 会自动变身成可以上下卷动的选单
    controller.addAction(action) 
}
let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
controller.addAction(cancelAction)
present(controller, animated: true, completion: nil)

明天会介绍：

1. 显示多个按钮
2. 在 alert 里显示 TextField

敬请期待！