我如何传递一个控制器的功能

Question

你好，我有我已经宣布AlertViewFunction这样

func displayAlertMessage(userMessage: String,//controller){ 
    let myAlert = UIAlertController(title: "Alert", message: userMessage, preferredStyle: UIAlertControllerStyle.Alert); 
    let okAction = UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil) 
    myAlert.addAction(okAction); 
    self.presentViewController(myAlert, animated: true, completion: nil)  
} 

的问题是一个工具类，我不能使用self这里

self.presentViewController(myAlert, animated: true, completion: nil) 

我想通过一个控制器到这个功能，所以我可以这样使用

controller.presentViewController(myAlert, animated: true, completion: nil) 

如何通过控制器来自任何ViewController。比方说，如果我在LoginViewController

Utility().displayAlertMessage(Message.INTERNETISNOTCONNECTED,//controller) 

Answer 1

Utility().displayAlertMessage(Message.INTERNETISNOTCONNECTED, controller: self) 

和

func displayAlertMessage(userMessage: String, controller: UIViewController) 
{ 
    controller?.presentViewController(myAlert, animated: true, completion: nil) 
} 

Answer 2

通在视图控制器作为参数传递给函数。

func displayAlertMessage(controller: UIViewController, title: String, message: String?) { 
    let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert) 
    let okAction = UIAlertAction(title: "Ok", style: .Default, handler: nil) 
    alert.addAction(okAction) 
    controller.presentViewController(alert, animated: false, completion: nil) 
} 

或者你甚至可以提醒说返回进一步定制函数的调用者：

func displayAlertMessage(title: String, message: String?) -> UIAlertController { 
    let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert) 
    let okAction = UIAlertAction(title: "Ok", style: .Default, handler: nil) 
    alert.addAction(okAction) 
    return alert 
} 

class controller: UIViewController { 
    override func viewDidLoad() { 
    super.viewDidLoad() 
    let alert = displayAlertMessage("title", message: nil) 
    presentViewController(alert, animated: true, completion: nil) 
    } 
}