当用户将手指从屏幕上松开时，使用 Xcode 中的委托函数生成图像

Question

I am trying to learn to build a simple app and i keep running into the issue of delegate. I have two classes one which is setting up the original images for the app and allowing them to be moved around by the user. The other class is the ViewController class which is where I am writing the code for the delegation to create the other object that appears when the user releases the initial object on the app.

In the View Controller class the code I have written is: enter image description here

I am trying to get it to work with the function "func endtouches" in the other class however I am unsure of how to do this.

Any help or guidance would be extremely appreciated

**edit

import UIKit

 protocol AppearBall {
    func addImage()

}

 class ViewController: UIViewController, AppearBall{



func addImage() {
    img = UIImage(contentsOfFile: "ShoeboxImageView.png")
}


var delegate: AppearBall?


@IBOutlet var img: UIImage!
@IBOutlet weak var ShoeboxImageView: DragImageView!

override func viewDidLoad() {
    super.viewDidLoad()

    ShoeboxImageView?.myDelegate = self




    func didReceiveMemoryWarning() {
 super.didReceiveMemoryWarning()
       // Dispose of any resources that can be recreated.


}

} }

Answer 1

Here's a simple pattern.

Start by creating a protocol, as you have. (But uppercase because it's a type.)

protocol ImageProducer {
    func addImage()
}

Create the class that will use a delegate to accomplish something.

class TouchHandler {
    var delegate: ImageProducer?

    func endTouches() {
        guard let del = delegate else {
            print("No delegate set")
            return
        }
        print("Sending delegate request")
        del.addImage()
    }
}

Provide an implementation of the delegate protocol. (This doesn't actually work because I don't have images. So, ignore anything other than handler/delegate interaction.)

class Worker: ImageProducer {
    var box: UIImageView?
    let img: UIImage?

    init() {
        img = UIImage(contentsOfFile: "somefile.png")
    }

    func startInteraction() {
        let handler = TouchHandler()
        handler.delegate = self
        handler.endTouches()
    }

    func addImage() {
        guard let image = img else {
            print("Image didn't get created")
            return
        }
        print("Creating image view")
        box = UIImageView(image: image)
    }
}