当视图未出现在第一个viewDidLoad上时，UITapGesture不起作用

Question

我有2个视图，每个视图都有自己的UITapGestureRecognizer。当视图在首次加载时出现时，轻击手势功能可以完美工作。但是当视图没有出现在第一个负载上时，这意味着我必须先滚动它才能查看视图，突然间，轻击手势不起作用。这怎么发生的？这是我的代码

import UIKit

class EditorTwitterViewController: UIViewController {

@IBOutlet weak var mainScrollView: UIScrollView!
@IBOutlet weak var contentTitleLabel: UILabel!
@IBOutlet weak var dateActivityLabel: UILabel!
@IBOutlet weak var statusViewHeight: NSLayoutConstraint!

@IBOutlet weak var photosViewHeight: NSLayoutConstraint!
@IBOutlet weak var collectionView: UICollectionView!
@IBOutlet weak var tableView: UITableView!

@IBOutlet weak var approveView: UIView!
@IBOutlet weak var approveImageView: UIImageView!
@IBOutlet weak var approveLabel: UILabel!

@IBOutlet weak var rejectView: UIView!
@IBOutlet weak var rejectImageView: UIImageView!
@IBOutlet weak var rejectLabel: UILabel!

@IBOutlet weak var noteViewHeight: NSLayoutConstraint!
@IBOutlet weak var noteTextView: UITextView!

var hasStatus: Bool?
var numberOfPhotos = 5
var numberOfRows = 3

override func viewDidLoad() {
    super.viewDidLoad()

    hasStatus = false
    noteTextView.placeholder = "Note"
    noteIsVisible(tag: 0)

    setupTableView()
    setupStatusView()

    self.collectionView.register(UINib(nibName: "ImagesCell", bundle: nil), forCellWithReuseIdentifier: "ImagesCell")
    self.collectionView.reloadData()
    self.setupApprovalView()

}

override func viewDidAppear(_ animated: Bool) {
    self.setupMainScrollView()
}

private func setupTableView() {

    self.tableView.register(UINib(nibName: "TwitterEditorCell", bundle: nil), forCellReuseIdentifier: "TwitterEditorCell")
    self.tableView.rowHeight = 250
    self.tableView.estimatedRowHeight = UITableViewAutomaticDimension

}

private func setupMainScrollView() {

    let photosViewHeight = CGFloat(54 * numberOfPhotos)
    let scrollViewHeight = 800 + photosViewHeight
    self.photosViewHeight.constant = photosViewHeight
    self.mainScrollView.contentSize.height = scrollViewHeight
    self.mainScrollView.keyboardDismissMode = .onDrag
    self.view.setNeedsLayout()
    self.view.setNeedsUpdateConstraints()

}

private func setupStatusView() {

    if hasStatus! {
        self.statusViewHeight.constant = 44
    } else {
        self.statusViewHeight.constant = 0
    }

    self.view.setNeedsUpdateConstraints()
}

private func setupApprovalView() {

    let approved = UITapGestureRecognizer(target: self, action: #selector(changeStatus(sender:)))
    let rejected = UITapGestureRecognizer(target: self, action: #selector(changeStatus(sender:)))

    approveView.addGestureRecognizer(approved)
    rejectView.addGestureRecognizer(rejected)

}

@objc private func changeStatus(sender: UIGestureRecognizer) {

    print(sender.view?.tag ?? "")
    if sender.view?.tag == 0 {
        approveImageView.image = UIImage(named: "approvegreen")
        approveLabel.textColor = UIColor.greenWithHex

        rejectImageView.image = UIImage(named: "rejected")
        rejectLabel.textColor = UIColor.blackWithHex

    } else if sender.view?.tag == 1 {
        approveImageView.image = UIImage(named: "approve")
        approveLabel.textColor = UIColor.blackWithHex

        rejectImageView.image = UIImage(named: "rejectedred")
        rejectLabel.textColor = UIColor.redWithHex
    }

    noteIsVisible(tag: sender.view!.tag)
}

private func noteIsVisible(tag: Int) {
    if tag == 0 {
        noteViewHeight.constant = 0
    } else if tag == 1 {
        noteViewHeight.constant = 150
    }

    self.view.setNeedsUpdateConstraints()
}

}

其中mainScrollView是父视图的主滚动视图，setupApprovalView（）是为每个视图初始化UITapGesture的函数，而changeStatus（）是在单击该视图时发生的函数