结果页面上的空白屏幕：它去了哪里？

Posted 2023-02-23

【中文标题】结果页面上的空白屏幕：它去了哪里？

【英文标题】：blank screen on results page: where did it go?

【发布时间】：2018-05-03 16:34:18

【问题描述】：

在这个阶段，应用程序应该显示测验的结果。因为我希望名称显示在与描述不同的行上/以不同的字体显示，所以我将其分成两个标签。目前，这两个标签都没有出现。我认为这个问题来自 setUpViews 和/或约束，但我不确定。

import UIKit
class ResultsController: UIViewController 

let resultsLabel: UILabel = 
    let rlbl = UILabel()
    rlbl.text = "Congratulations!"
    rlbl.contentMode = .scaleToFill
    rlbl.numberOfLines = 0
    rlbl.translatesAutoresizingMaskIntoConstraints = false
    rlbl.textAlignment = .center
    rlbl.font = UIFont(name: "USIS 1949", size: 50)
    rlbl.adjustsFontSizeToFitWidth = true
    rlbl.numberOfLines=0
    rlbl.sizeToFit()
    rlbl.minimumScaleFactor = 0.1
    return rlbl
()

let descriptionLabel: UILabel = 
    let dlbl = UILabel()
    dlbl.text = "Congratulations!"
    dlbl.contentMode = .scaleToFill
    dlbl.numberOfLines = 0
    dlbl.translatesAutoresizingMaskIntoConstraints = false
    dlbl.textAlignment = .justified
    dlbl.font = UIFont(name: "Flama", size: 30)
    return dlbl
()

func setupViews() 
    self.view.addSubview(resultsLabel)
    resultsLabel.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 150).isActive=true
    resultsLabel.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive=true
    resultsLabel.widthAnchor.constraint(equalToConstant: 500).isActive=true

    self.view.addSubview(descriptionLabel)
    descriptionLabel.topAnchor.constraint(equalTo: resultsLabel.bottomAnchor, constant: 20).isActive=true
    descriptionLabel.heightAnchor.constraint(equalToConstant: 50).isActive=true
    descriptionLabel.widthAnchor.constraint(equalToConstant: 150).isActive=true
    descriptionLabel.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive=true
    descriptionLabel.centerYAnchor.constraint(equalTo: self.view.centerYAnchor, constant: 0).isActive=true


override func viewDidLoad() 
    super.viewDidLoad()

    navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Done", style: .plain, target: self, action: #selector(done(sender:)))

    navigationItem.title = "Results"

    view.backgroundColor = UIColor.white

    let names = ["Ross", "Joey", "Chandler", "Monica", "Rachel", "Phoebe"]

    let additional = ["Ross", "Joey", "Chandler", "Monica", "Rachel", "Phoebe"]

    var score = 0
    for question in QuestionController.questionsList 
        score += question.selectedAnswerIndex!
    

    let result = names[score % names.count]
    resultsLabel.text = "\(result)"

    let description = additional[score % additional.count]
    descriptionLabel.text = "\(description)"



    @objc func done(sender: UIBarButtonItem) 

    navigationController?.popToRootViewController(animated: true)





class QuestionHeader: UITableViewHeaderFooterView 

override init(reuseIdentifier: String?) 
    super.init(reuseIdentifier: reuseIdentifier)
    setupViews()


let nameLabel: UILabel = 
    let label = UILabel()
    label.text = "Sample Question"
    label.font = UIFont.boldSystemFont(ofSize: 30)
    label.translatesAutoresizingMaskIntoConstraints = false
    return label
()

func setupViews() 
    addSubview(nameLabel)
    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-16-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))
    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))


required init?(coder aDecoder: NSCoder) 
    fatalError("init(coder:) has not been implemented")




class AnswerCell: UITableViewCell 

override init(style: UITableViewCellStyle, reuseIdentifier: String?) 
    super.init(style: style, reuseIdentifier: reuseIdentifier)
    setupViews()


required init?(coder aDecoder: NSCoder) 
    fatalError("init(coder:) has not been implemented")


let nameLabel: UILabel = 
    let label = UILabel()
    label.text = "Sample Answer"
    label.font = UIFont.systemFont(ofSize: 30)
    label.translatesAutoresizingMaskIntoConstraints = false
    return label
()

func setupViews() 
    addSubview(nameLabel)
    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-16-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))
    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))


 

【参考方案1】：

如果指的是ResultsController，您不是在viewDidLoad() 中调用setUpViews()。

【讨论】：

那么我只需要移动 setUpViews() 吗？

在您提供的代码中，您实现了 setUpViews 方法，但从不使用它。在方法 viewDidLoad 中的 super.viewDidLoad() 之后添加 setUpViews() 行