iOS Swift - 来自其他类的函数不运行

Question

我想创建一个具有模糊 View 的类，如果出现任何问题，该类应该出现在现有 View 上。这是代码:

import Foundation
import UIKit

class checkProblems{

    let effectView:UIVisualEffectView = UIVisualEffectView (effect: UIBlurEffect(style: UIBlurEffectStyle.Light))
    var view: UIView
    let label = UILabel()
    let retry = UIButton()

    init(view: UIView){
        self.view = view
        self.check()
    }

    func check(){
        effectView.frame = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height)
        label.frame = CGRectMake(0, (self.view.frame.height/2)-20, self.view.frame.width, 40)
        label.text = "Server connection problems."
        label.textAlignment = NSTextAlignment.Center
        label.textColor = UIColor.darkGrayColor()
        label.font = UIFont (name: "HelveticaNeue-Light", size: 20)

        retry.frame = CGRectMake(0, (self.view.frame.height/2)+10, self.view.frame.width, 40)
        retry.setTitle("Tap here to retry.", forState: UIControlState.Normal)
        retry.addTarget(self, action: "pressed:", forControlEvents: .TouchUpInside)

        self.view.addSubview(effectView)
        effectView.addSubview(label)
        effectView.addSubview(retry)
    }

    func pressed(sender: UIButton!){
       println("here")
    }
}

这就是我在 View Controller 上调用它的方式:

let checkObject = checkProblems(view: view)

一切正常，直到我按下“点击此处重试”按钮。然后，我的应用程序崩溃了。

Answer 1

我认为您的方法打破了 MVC 模式。其次是addAction方法对应引用的问题。请将所有 View 创建或交替代码添加到 viewController。这将使您的应用程序更容易理解。我更改了您的代码以正确实现 MVC 模式(并使其完全可运行)

import UIKit

class ViewController: UIViewController {

  let effectView:UIVisualEffectView = UIVisualEffectView (effect: UIBlurEffect(style: UIBlurEffectStyle.Light))
  let label = UILabel()
  let retry = UIButton()

  override func viewDidLoad() {
    super.viewDidLoad()        
    check()
  }

  func check(){
    effectView.frame = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height)
    label.frame = CGRectMake(0, (self.view.frame.height/2)-20, self.view.frame.width, 40)
    label.text = "Server connection problems."
    label.textAlignment = NSTextAlignment.Center
    label.textColor = UIColor.darkGrayColor()
    label.font = UIFont (name: "HelveticaNeue-Light", size: 20)

    retry.frame = CGRectMake(0, (self.view.frame.height/2)+10, self.view.frame.width, 40)
    retry.backgroundColor = .blueColor()
    retry.setTitle("Tap here to retry.", forState: UIControlState.Normal)
    retry.addTarget(self, action: "pressed:", forControlEvents: UIControlEvents.TouchUpInside)

    effectView.addSubview(label)
    effectView.addSubview(retry)
    view.addSubview(effectView)    
  }
  func pressed(sender: UIButton){
    println("here")
  }
}

除了您的评论之外，我还向您展示了一个 MVC 保护方法的示例，它将子类化 UIViewController。然后，您可以使用 presentViewController 加载 checkProblems 类:

来自调用 VC 的代码:

import UIKit    
  class ViewController: UIViewController {
    override func viewDidLoad() {
      super.viewDidLoad()
        }
    override func viewDidAppear(animated: Bool) {
      super.viewDidAppear(animated)
      let checkProblemsVC = CheckProblemsViewController()
      presentViewController(checkProblemsVC, animated: true, completion: nil)
    }
  }

以及新的子类 CheckProblemsViewController:

    import UIKit

class CheckProblemsViewController: UIViewController {

  let effectView:UIVisualEffectView = UIVisualEffectView (effect: UIBlurEffect(style: UIBlurEffectStyle.Light))
  let label = UILabel()
  let retry = UIButton()

  override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    check()
  }

  func check(){
    effectView.frame = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height)
    label.frame = CGRectMake(0, (self.view.frame.height/2)-20, self.view.frame.width, 40)
    label.text = "Server connection problems."
    label.textAlignment = NSTextAlignment.Center
    label.textColor = UIColor.darkGrayColor()
    label.font = UIFont (name: "HelveticaNeue-Light", size: 20)

    retry.frame = CGRectMake(0, (self.view.frame.height/2)+10, self.view.frame.width, 40)
    retry.backgroundColor = .blueColor()
    retry.setTitle("Tap here to retry.", forState: UIControlState.Normal)
    retry.addTarget(self, action: "pressed:", forControlEvents: UIControlEvents.TouchUpInside)

    effectView.addSubview(label)
    effectView.addSubview(retry)
    view.addSubview(effectView)

  }

  func pressed(sender: UIButton){
    println("here")
  }


}