ios - 在运行 xcode 8 的 swift 模拟器中查看对象未显示

Question

我一直在将 Food Tracker 应用教程作为学习 Swift 的项目。我知道这充满了错误，但我一直在研究正确格式化代码的方法。我进入星级部分，添加了红色按钮，将其分成 5 个按钮，然后添加了星星。星星出现了一段时间，但现在根本没有出现在我的模拟器中。我已经清理了我的代码，断开连接并添加了图像和图像代码，断开连接并添加了我的 IBOutlet 等。它们仍然没有显示，所以我认为我的代码中一定缺少一些东西，因为我是新手。任何帮助将非常感激。

import UIKit

class RatingControl: UIView {
    // MARK: Properties

    var rating = 0 {
        didSet {
            setNeedsLayout()
        }
    }
    var ratingButtons = [UIButton]()
    var spacing = 5
    var stars = 5

    // MARK: Initialization

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

        let filledStar = UIImage(named: "filledStar")
        let emptyStar = UIImage(named: "emptyStar")

        for _ in 0..<5 {
            let button = UIButton()

            button.setImage(emptyStar, for: UIControlState())
            button.setImage(filledStar, for: .selected)
            button.setImage(filledStar, for: [.highlighted, .selected])

            button.adjustsImageWhenHighlighted = false

            button.addTarget(self, action: #selector(RatingControl.ratingButtonTapped(_:)), for: .touchDown);            ratingButtons += [button]
            addSubview(button)
        }
    }

    override func layoutSubviews() {
        // Set the button's width and height to a square the size of the frame's height.
        let buttonSize = Int(frame.size.height)
        var buttonFrame = CGRect(x: 0, y: 0, width: buttonSize, height: buttonSize)

        // Offset each button's origin by the length of the button plus spacing.
        for (index, button) in ratingButtons.enumerated() {
            buttonFrame.origin.x = CGFloat(index * (buttonSize + spacing))
            button.frame = buttonFrame
        }
        updateButtonSelectionStates()
    }

    override var intrinsicContentSize : CGSize {
        let buttonSize = Int(frame.size.height)
        let width = (buttonSize + spacing) * stars

        return CGSize(width: width, height: buttonSize)
    }

    // MARK: Button Action

    func ratingButtonTapped(_ button: UIButton) {
        rating = ratingButtons.index(of: button)! + 1

        updateButtonSelectionStates()
    }

    func updateButtonSelectionStates() {
        for (index, button) in ratingButtons.enumerated() {
            // If the index of a button is less than the rating, that button should be selected.
            button.isSelected = index < rating
        }
    }
}

Answer 1

在你的 init?() 方法中，你错过了向 ratingButtons 数组添加按钮，因此当枚举和访问该数组时什么也没有出现，并且它是空的

请添加以下内容

self.ratingsButton.append(button)

紧接着

addSubview(button)

希望按钮能够开始显示。