在應用中有很多的彈窗坑定是需要的，這裡隨便寫了幾個系統的UIAlertController的簡單應用，主要有四個

1，常規彈窗，確定按鈕，取消按鈕，或者只有確定，或者取消按鈕；

2，選擇圖片的從底部滑動的彈窗；

3，帶輸入框的彈窗

4，一閃而過的彈框，但是這種樣式寫死，沒法改變背景顏色等等這些東西；

程式碼如下

import UIKit

class AlertController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        let button = UIButton();
        button.frame = CGRect.init(x: 20, y: 100, width: UIScreen.main.bounds.width - 2*20, height: 56);
        button .titleLabel?.font = UIFont.systemFont(ofSize: 16);
        button.setTitle("確定取消只展示訊息", for: UIControlState.normal)
        button .setTitleColor(UIColor .red, for: UIControlState.normal);
        
        button .backgroundColor = UIColor.orange;
        button.addTarget(self, action: #selector(alertTypeNormal), for: UIControlEvents.touchUpInside)
        self.view .addSubview(button);
        
        let sheetBtn = UIButton();
        sheetBtn.frame = CGRect.init(x: 20, y: 156+20 , width: UIScreen.main.bounds.width - 2*20, height: 56);
        sheetBtn .titleLabel?.font = UIFont.systemFont(ofSize: 16);
        sheetBtn.setTitle("底部滑出", for: UIControlState.normal)
        sheetBtn .setTitleColor(UIColor .red, for: UIControlState.normal);
        
        sheetBtn .backgroundColor = UIColor.gray;
        sheetBtn.addTarget(self, action: #selector(alertSheet), for: UIControlEvents.touchUpInside)
        self.view .addSubview(sheetBtn);
        
        let logBtn = UIButton();
        logBtn.frame = CGRect.init(x: 20, y: 156+20 + 76 , width: UIScreen.main.bounds.width - 2*20, height: 56);
        logBtn .titleLabel?.font = UIFont.systemFont(ofSize: 16);
        logBtn.setTitle("帶有textField控制元件的", for: UIControlState.normal)
        logBtn .setTitleColor(UIColor .red, for: UIControlState.normal);
        
        logBtn .backgroundColor = UIColor.green;
        logBtn.addTarget(self, action: #selector(alertTF), for: UIControlEvents.touchUpInside)
        self.view .addSubview(logBtn);
        
        let disBtn = UIButton();
        disBtn.frame = CGRect.init(x: 20, y: 156+20 + 76 + 76 , width: UIScreen.main.bounds.width - 2*20, height: 56);
        disBtn .titleLabel?.font = UIFont.systemFont(ofSize: 16);
        disBtn.setTitle("一閃而過的效果", for: UIControlState.normal)
        disBtn .setTitleColor(UIColor .red, for: UIControlState.normal);
        
        disBtn .backgroundColor = UIColor.brown;
        disBtn.addTarget(self, action: #selector(alertDismiss), for: UIControlEvents.touchUpInside)
        self.view .addSubview(disBtn);
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    /**一般彈窗型別 有確定和取消，可以只有一個按鈕的將action修改就可以了
     destructive  使用此風格 字型顏色為紅色 其他型別位系統預設的藍色**/
    func alertTypeNormal(){
        let alertNormal = UIAlertController(title: "系統提示", message: "無上的神偉大的小明", preferredStyle: .alert)
        let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
        let sureAction = UIAlertAction(title: "確定", style: .destructive) { (UIAlertAction) in
            print("點選了確定")
        }
        alertNormal.addAction(cancelAction);
        alertNormal.addAction(sureAction);
        self.present(alertNormal, animated: true) {
            
        }
    }
    /**一般用於選擇圖片或者拍照的彈框從底部滑出**/
    func alertSheet(){
        let alertsheet = UIAlertController(title: "請選擇圖片或拍攝圖片", message: "", preferredStyle: .actionSheet)
        let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: { (UIAlertAction) in
            print("選擇了取消");

        })
        let  photoAction = UIAlertAction(title: "相機", style: .default) { (UIAlertAction) in
            print("選擇了相機");
        }
        let tumbAction = UIAlertAction(title: "相簿", style: .default) { (UIAlertAction) in
            print("選擇了相簿");
        }
        alertsheet.addAction(cancelAction);
        alertsheet.addAction(photoAction);
        alertsheet.addAction(tumbAction);
        
        self.present(alertsheet, animated: true) {
            
        }
    }
    /**帶有輸入框的彈窗**/
    func alertTF(){
        let alertController = UIAlertController(title: "登入頁面",message: "輸入使用者名稱和密碼", preferredStyle: .alert)
        alertController.addTextField {
            (textField: UITextField!) -> Void in
            textField.placeholder = "請輸入使用者名稱"
        }
        alertController.addTextField {
            (textField: UITextField!) -> Void in
            textField.placeholder = "請輸入密碼"
            textField.isSecureTextEntry = true
        }
        let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
        let okAction = UIAlertAction(title: "登入", style: .default, handler: {
            action in
            //也可以用下標的形式獲取textField let login = alertController.textFields![0]
            let login = alertController.textFields!.first!
            let password = alertController.textFields!.last!
            print("使用者名稱：\(login.text) 密碼：\(password.text)")
        })
        alertController.addAction(cancelAction)
        alertController.addAction(okAction)
        self.present(alertController, animated: true, completion: nil)
    }
    /**規定時間後消失的彈框**/
    func alertDismiss(){
    let alertController = UIAlertController(title: "儲存成功!",message: nil, preferredStyle: .alert)
        
        //顯示提示框
        self.present(alertController, animated: true, completion: nil)
                    //兩秒鐘後自動消失
        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 2) {
        self.presentedViewController?.dismiss(animated: false, completion: nil)
        
        }

    
    }
    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}