ios - UIButtons 未显示在 UIScrollView 中

Question

我正在尝试获取一个电子邮件地址，从中创建一个按钮，然后将该按钮添加到 UIScrollView 中。

问题是按钮在 UIScrollView 中不可见。电子邮件正在添加到列表中，按钮正在创建但不可见。

代码:

import UIKit

let BUTTON_SPACING = 10
let BUTTON_HEIGHT = 40

class ViewController: UIViewController {

@IBOutlet weak var mailField: UITextField!
@IBOutlet weak var scrollView: UIScrollView!

var fileUrl = NSURL()
var emails = [String]()

var mailButtArr: [UIButton] = []
var deletButtArr: [UIButton] = []

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
    print(documentsURL)
    fileUrl = documentsURL.appendingPathComponent("emails.plist") as NSURL

    let fileManager = FileManager.default
    if(!fileManager.fileExists(atPath: fileUrl.path!))
    {
        print("email.plist is not found with filemanager")
        NSKeyedArchiver.archiveRootObject(emails, toFile: fileUrl.path!)
    }
    else
    {
        emails = NSKeyedUnarchiver.unarchiveObject(withFile: fileUrl.path!) as! [String]
        print(emails.count, " emails found ")
        for s in emails
        {
            print(s)
            addNewButton(title: s)
        }
    }
    mailField.text = "xyz@mail.com"
}

@IBAction func AddEmail(sender: AnyObject)
{
    mailField.resignFirstResponder()

    let email: String = mailField.text!

    emails.append(email)
    mailField.text = "xyz@mail.com"

    NSKeyedArchiver.archiveRootObject(emails, toFile: fileUrl.path!)
    print("saved")

    addNewButton(title: email)
}

@objc func buttonTouched(sender: UIButton)
{
    let urlString: String = sender.titleLabel!.text!
    let url: NSURL = NSURL(string: urlString)!
    UIApplication.shared.openURL(url as URL)
}

func addNewButton(title: String)
{
    let butt: UIButton = UIButton()
    butt.setTitle(title, for: .normal)

    butt.backgroundColor = UIColor.green
    butt.layer.borderColor = UIColor.black.cgColor
    butt.layer.borderWidth = 0.5
    butt.layer.cornerRadius = 10.0

    butt.addTarget(self, action: #selector(ViewController.buttonTouched(sender:)), for: .touchUpInside)
    mailButtArr.append(butt)
    mailButtArr = mailButtArr.sorted {$0.titleLabel!.text! < $1.titleLabel!.text!}

    let newHeight: Float = Float((mailButtArr.count) * (BUTTON_HEIGHT + BUTTON_SPACING)) + Float(BUTTON_SPACING)
    let contentSize: CGSize = CGSize(width: scrollView.frame.size.width, height: CGFloat(newHeight))

    scrollView.contentSize = contentSize

    refreshList()
}

func refreshList()
{
    let subviews = scrollView.subviews as [UIView]
    for v in subviews
    {
        if let button = v as? UIButton
        {
            button.removeFromSuperview()
        }
    }
    deletButtArr.removeAll()

    var buttonOffset: CGFloat = CGFloat(BUTTON_SPACING)

    for button: UIButton in mailButtArr
    {
        var buttonFrame: CGRect = button.frame
        buttonFrame.origin.x = CGFloat(BUTTON_SPACING)
        buttonFrame.origin.y = buttonOffset

        buttonFrame.size.width = 200
        buttonFrame.size.height = CGFloat(BUTTON_HEIGHT)
        print("X:", BUTTON_SPACING, " Y:", buttonOffset, " W: ", buttonFrame.size.width, " H: ", BUTTON_HEIGHT)
        scrollView.addSubview(button)

       /* let delButt: UIButton = UIButton(type: .detailDisclosure)
        deletButtArr.append(delButt)
        buttonFrame = delButt.frame
        buttonFrame.origin.x = 340
        buttonFrame.origin.y = buttonOffset + 10
        delButt.frame = buttonFrame

        scrollView.addSubview(delButt)*/

        buttonOffset += CGFloat(BUTTON_HEIGHT + BUTTON_SPACING)
    }
}

}

此代码的大部分内容是从类演示中复制的，我正在尝试针对作业进行修改。

Answer 1

好吧，根据这段代码，我从一开始就发现了一些问题。

您的 addNewButton 函数创建一个按钮，但不设置框架或约束，并且仅将该按钮添加到数组中。

首先，我在想另一个答案所说的，您没有将按钮添加到 View 中，但后来我看到您确实在 refreshList 函数上将按钮添加到了 View 中。

在该函数中，您实际上创建了一个按钮框架，但在添加到 View 之前从未将该框架分配给按钮。

因此，您的情况下的第一个测试是在 scrollView.addSubview(button) 添加之前:button.frame = buttonFrame 看看是否有效