Question

我有一个ViewController，其中包含名为myView的UIView和名为myImageView的UIImageView。在下面的代码中，我有一个名为viewLine的类，它附加到名为myView的UIView。

我遇到的麻烦是调用touchesEnded时，我想在ViewController中更改myImageView的alpha。当我尝试这个时，myImageView的alpha值没有变化。

（或者，当我尝试通过将viewLine类移动到主ViewController中来实现此目的时，会出现以下错误 - override func drawRect(rect: CGRect) - Method不会覆盖其超类中的任何方法< / em>和self.setNeedsDisplay() - “ViewController”类型的值没有成员'setNeedsDisplay'。）

问题：

1 - 如何修改名为viewLine的类中的代码以访问ViewController故事板上的其他UI对象或函数，例如myImageView？即，在myImageView被调用后，如何更改viewLine类中touchesEnded的alpha？

2 - 我在ViewController中有一个滑块sliderLineSize，在ViewController中有一个变量lineSize。 UISlider sliderLineSize更改lineSize。但是，lineSize类的drawRect部分使用了viewLine。如何传递或访问类中ViewController中的变量集？

（3 - 如何将viewLine类合并到主ViewController中？）

import UIKit class ViewController: UIViewController { @IBOutlet weak var myView: UIView! @IBOutlet weak var myImageView: UIImageView! var lineSize: Int = 1 override func viewDidLoad() { super.viewDidLoad() } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() } override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) { myImageView.alpha = 0.5 } @IBAction func sliderLineSize(sender: UISlider) { lineSize = Int(sender.value) } } class viewLine: UIView { let path=UIBezierPath() var incrementalImage:UIImage? var previousPoint:CGPoint = CGPoint.zero var strokeColor:UIColor? required init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder) } override func drawRect(rect: CGRect) { incrementalImage?.drawInRect(rect) path.lineWidth = lineSize path.stroke() } override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) { let touch: AnyObject? = touches.first let currentPoint = touch!.locationInView(self) path.moveToPoint(currentPoint) previousPoint=currentPoint self.setNeedsDisplay() } override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) { let touch: AnyObject? = touches.first let currentPoint = touch!.locationInView(self) let midPoint = self.midPoint(previousPoint, p1: currentPoint) path.addQuadCurveToPoint(midPoint,controlPoint: previousPoint) previousPoint=currentPoint path.moveToPoint(midPoint) self.setNeedsDisplay() } override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) { self.drawBitmap() self.setNeedsDisplay() path.removeAllPoints() } func midPoint(p0:CGPoint,p1:CGPoint)->CGPoint { let x=(p0.x+p1.x)/2 let y=(p0.y+p1.y)/2 return CGPoint(x: x, y: y) } func drawBitmap() { UIGraphicsBeginImageContextWithOptions(self.bounds.size, true, 1) strokeColor?.setStroke() if((incrementalImage) == nil){ let rectPath:UIBezierPath = UIBezierPath(rect: self.bounds) UIColor.whiteColor().setFill() rectPath.fill() } incrementalImage?.drawAtPoint(CGPointZero) path.stroke() incrementalImage = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() } }

Answer 1

我查看了如何从其子视图引用ViewController，我发现最好的赌注是StackOverflow回答说＆＃34;遵循MVC模式，ViewController知道它的视图，但视图不应该是了解ViewController。相反，你应该声明委托协议＆＃34; （来源：Swift - How to pass a view controller's reference to a sub UIView class?）

所以，我的解决方案是编写自定义委托协议并使ViewController遵守它。上述答案中的代码有点过时，无法编写委托协议，但Pure Swift class conforming to protocol with static method - issue with upcasting中问题的开头显示了如何正确编写适用于我的Xcode 7.2的协议。

我的故事板上有这样的图表：

查看
- 我的观点（链接到您的代码）
- 我的图像视图（背景是我选择的静态图像）

我将类viewLine重命名为ViewLineUIView，因为我认为它将是底层超类的更具描述性的名称。代码如下。

代码：

import UIKit

protocol ViewLineUIViewDelegate: class {
    func onTouchesEnded(viewLine: ViewLineUIView)
}

class ViewController: UIViewController, ViewLineUIViewDelegate {

    @IBOutlet weak var myView: UIView!
    @IBOutlet weak var myImageView: UIImageView!
    @IBOutlet weak var sliderValue: UISlider!

    var viewLineDelegate: ViewLineUIView!

    override func viewDidLoad() {
        super.viewDidLoad()
        viewLineDelegate = myView as? ViewLineUIView
        viewLineDelegate!.delegate = self

        //update lineWidth to initial value of slider
        updateLineWidth()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func onTouchesEnded(viewLine: ViewLineUIView) {
        myImageView!.alpha = 0.5
    }

    //Updating lineWidth!
    @IBAction func onSliderChange(sender: UISlider) {
        updateLineWidth()

    }

    func updateLineWidth() {
        let drawView = myView as! ViewLineUIView
        //you can change this "10" value to your max lineWidth
        drawView.path.lineWidth = CGFloat(sliderValue.value*10)
        print("New value is: " + String(drawView.path.lineWidth))
    }


}

class ViewLineUIView: UIView {

    weak var delegate: ViewLineUIViewDelegate?

    let path=UIBezierPath()
    var incrementalImage:UIImage?
    var previousPoint:CGPoint = CGPoint.zero
    var strokeColor:UIColor?

    required init?(coder aDecoder: NSCoder) {
        //Initialize lineWidth so that compiler doesn't complain
        super.init(coder: aDecoder)
    }

    override func drawRect(rect: CGRect) {
        incrementalImage?.drawInRect(rect)
        path.stroke()
    }

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        let touch: AnyObject? = touches.first
        let currentPoint = touch!.locationInView(self)
        path.moveToPoint(currentPoint)
        previousPoint=currentPoint
        self.setNeedsDisplay()
    }

    override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
        let touch: AnyObject? = touches.first
        let currentPoint = touch!.locationInView(self)
        let midPoint = self.midPoint(previousPoint, p1: currentPoint)
        path.addQuadCurveToPoint(midPoint,controlPoint: previousPoint)
        previousPoint=currentPoint
        path.moveToPoint(midPoint)
        self.setNeedsDisplay()
    }

    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
        self.drawBitmap()
        self.setNeedsDisplay()
        path.removeAllPoints()

        delegate?.onTouchesEnded(self)
    }

    func midPoint(p0:CGPoint,p1:CGPoint)->CGPoint {
        let x=(p0.x+p1.x)/2
        let y=(p0.y+p1.y)/2
        return CGPoint(x: x, y: y)
    }

    func drawBitmap() {
        UIGraphicsBeginImageContextWithOptions(self.bounds.size, true, 1)
        strokeColor?.setStroke()
        if((incrementalImage) == nil){
            let rectPath:UIBezierPath = UIBezierPath(rect: self.bounds)
            UIColor.whiteColor().setFill()
            rectPath.fill()
        }
        incrementalImage?.drawAtPoint(CGPointZero)
        path.stroke()
        incrementalImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
    }

}

如您所见，编辑路径的lineWidth非常简单，您不需要创建另一个委托协议。 ViewController可以直接访问其子视图。你应该知道需要演员。

从Swift中的另一个类访问ViewController中的对象

1 个答案: