swift - Swift 中的 UIScrollView 子类用于触摸开始和触摸移动

Question

我正在使用 Swift 1.2

我正在尝试使用这个 UIScrollview touchesbegan,touchesmoved,touchesended actions以及已接受答案的第二条评论中的链接。

我正在使用具有自动布局的 Storyboard，我在自定义类中为 UIScrollView 设置了自定义类。

我在包含我的自定义 UIScrollView 的 UIViewController 中没有收到这些触摸事件中的任何一个

编辑:根据@Victor Sigler 的回答更新了我的代码以了解我如何使用它。

自定义 ScrollView 代码:

import UIKit

protocol PassTouchesScrollViewDelegate {

func scrollTouchBegan(touches: Set<NSObject>, withEvent event: UIEvent)
func scrollTouchMoved(touches: Set<NSObject>, withEvent event: UIEvent)
}

class PassTouchesScrollView: UIScrollView {

var delegatePass : PassTouchesScrollViewDelegate?

override init(frame: CGRect) {
    super.init(frame: frame)
}

required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {

    self.delegatePass?.scrollTouchBegan(touches, withEvent: event)


}

override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent) {

    self.delegatePass?.scrollTouchMoved(touches, withEvent: event)

}

}

我的 View Controller :

import UIKit

class ViewController: UIViewController, PassTouchesScrollViewDelegate {

@IBOutlet weak var scrollView: UIScrollView!

override func viewDidLoad() {
    super.viewDidLoad()

    scrollView.delegatePass = self
}

func scrollTouchBegan(touches: Set<NSObject>, withEvent event: UIEvent)    {

    println("began \(touches)")

}

func scrollTouchMoved(touches: Set<NSObject>, withEvent event: UIEvent)      {

    println("moved \(touches)")
}     

}

我试图让用户在 UIImage 上画一条线，我使用 PanGesture Recognizer 开始工作，但性能非常差，尤其是在较旧的硬件上，我遵循了 Ray Wenderlich 教程，该教程使用了 touches Began 和性能要好得多，但它是在 UIView 而不是 ScrollView 上。我需要一个 UIScrollView，因为在用户绘制图像之前，他们可以放大图像并围绕它放大。

Answer 1

你想错了。如果您想知道 UIScrollView 何时移动，则无需对其进行子类化。 iOS 已在 UIScrollViewDelegate 中设置了您需要的所有方法。

您必须实现 UISCrollViewDelegate通知有关 UIScrollView 中的操作并通过 Interface Builder 或在代码中设置 delegate，由您决定。

请参阅以下示例以了解如何执行此操作:

class ViewController: UIViewController, UIScrollViewDelegate {

     @IBOutlet weak var scrollView: UIScrollView!

     override func viewDidLoad() {
       super.viewDidLoad()
       self.scrollView.delegate = self
     }
}

不过，如果您想知道它是如何以您上面解释的方式触及的，您必须按照以下步骤操作:

1. 您必须像在类 PassTouchesScrollView 中那样从 UIScrollView 类创建子类，并实现委托(delegate)模式以接收有关 UIScrollView 以下列方式:

   import UIKit
   
   protocol PassTouchesScrollViewDelegate {
      func touchBegan()
      func touchMoved()
   }
   
   
   class PassTouchesScrollView: UIScrollView {
   
     var delegatePass : PassTouchesScrollViewDelegate?
   
     override init(frame: CGRect) {
       super.init(frame: frame)
     }
   
     required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
     }
   
     override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
   
        // Notify it's delegate about touched
        self.delegatePass?.touchBegan()
   
       if self.dragging == true {
          self.nextResponder()?.touchesBegan(touches, withEvent: event)
       } else {
          super.touchesBegan(touches, withEvent: event)
       }
   
    }
   
     override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent)  {
   
        // Notify it's delegate about touched
        self.delegatePass?.touchMoved()
   
        if self.dragging == true {            
           self.nextResponder()?.touchesMoved(touches, withEvent: event)
        } else {            
          super.touchesMoved(touches, withEvent: event)
        }
     }   
   }
   

2. 您的类 ViewController 必须按以下方式实现:

   class ViewController: UIViewController, UIScrollViewDelegate {
   
     @IBOutlet weak var scrollView: PassTouchesScrollView!
   
     override func viewDidLoad() {
       super.viewDidLoad()        
       scrollView.delegate = self  
       scrollView.delegatePass = self      
     }
   
     override func didReceiveMemoryWarning() {
       super.didReceiveMemoryWarning()
       // Dispose of any resources that can be recreated.
     }
   
     func touchMoved() {
        println("touch moved")
     }
   
     func touchBegan() {
        println("touch began")
     }
   
   }
   

3. 您必须在 Interface Builder 中选择您的 UIScrollView 并将其类设置为您的类 PassTouchesScrollView，在类部分的身份检查器中。

您应该会在控制台中看到以下内容:

touch began
touch began
touch began
touch began
touch began
touch began
touch moved
touch move

希望对你有帮助