Question

单击“颜色”navigation bar button时，会出现15种颜色的下拉菜单。下拉菜单占据屏幕高度和宽度的一半。用户可以向下滚动下拉菜单以查看所有颜色。但是，我现在的代码，单击导航栏按钮时没有任何反应。虽然出于测试目的，当我将滚动视图的背景颜色设置为更加可见时，我看到滚动视图占据了屏幕宽度和高度的一半。当我在view.addSubview(colorView)的末尾添加colorButtonTapped()时，我看到下拉显示屏占据了屏幕宽度的一半以及屏幕的所有高度。

AppDelegate:
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        window = UIWindow(frame: UIScreen.main.bounds)

        window?.rootViewController = UINavigationController(rootViewController: ViewController())
        window?.makeKeyAndVisible()
        return true
    }

import UIKit

class ViewController: UIViewController, UIScrollViewDelegate {
    var colorView: UIView!
    var scrollView: UIScrollView!

    override func viewDidLoad() {
        super.viewDidLoad()

        colorView = UIView()
        scrollView = UIScrollView()

        let colorButton = UIBarButtonItem(title: "Colors", style: .plain, target: self, action: #selector(colorButtonTapped))
        colorButton.setTitleTextAttributes([NSFontAttributeName: UIFont.systemFont(ofSize: 14.0), NSForegroundColorAttributeName: UIColor.black], for: UIControlState())
        navigationController?.navigationBar.topItem?.rightBarButtonItem = colorButton
    }

    func colorButtonTapped() {
        let colorOptions = ["Blue", "Black", "Red", "Green", "Yellow", "Purple", "Orange", "Pink", "Magenta", "Lavender", "Beige", "Tan", "Burgundy", "Eggshell", "Brown"]
        let buttonHeight: CGFloat = UIScreen.main.bounds.height / 15

        colorView.layer.cornerRadius = 8
        colorView.clipsToBounds = true

        //create options button
        for (index, title) in colorOptions.enumerated() {
            let button = UIButton(type: .custom)
            button.backgroundColor = .red

            button.frame = CGRect(x: 0, y: buttonHeight * CGFloat(index), width: colorView.frame.width, height: buttonHeight)
            button.setTitle(title, for: .normal)
            colorView.addSubview(button)
        }

        scrollView.delegate = self
        scrollView.contentSize = CGSize(width: UIScreen.main.bounds.width / 2.0, height: UIScreen.main.bounds.height / 2.0)
        scrollView.addSubview(colorView)
        view.addSubview(scrollView)
    }

    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        let y = (navigationController?.navigationBar.frame.height)! + UIApplication.shared.statusBarFrame.height
    scrollView.frame = CGRect(x: UIScreen.main.bounds.width / 2.0, y: y, width: UIScreen.main.bounds.width / 2.0, height: UIScreen.main.bounds.height / 2.0)
    colorView.frame = CGRect(x: UIScreen.main.bounds.width / 2.0, y: y, width: UIScreen.main.bounds.width / 2.0, height: UIScreen.main.bounds.height)
    }
}

Answer 1

每次调用scrollView时都无法更新colorView和viewWillLayoutSubviews的帧数。按下按钮即可创建。

下面的代码会将colorView的{{1}}和x的框架设置为y的右边缘，因此不可见< / em>的。两者都应scrollView将其定位到左边缘。

0

最后一个是colorView.frame = CGRect(x: UIScreen.main.bounds.width / 2.0, y: y, width: UIScreen.main.bounds.width / 2.0, height: UIScreen.main.bounds.height)的{{1}}属性。默认情况下，它已启用，因此它会从colorView吞下手势识别器。将其设置为isUserInteractionEnabled和enjoy。

为了在将来克服此类问题，我建议您阅读有关view debugging的更多信息。

scrollView

以编程方式创建可滚动的下拉菜单（iOS / Swift）

1 个答案: