我已经以编程方式创建了一个集合视图但是当设置collectionView.delegate = self和collectionView.dataSource = self时，我在解开一个可选项时得到一个nil。我不知道我在这里做错了什么。
class MainFeedViewController: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, UICollectionViewDelegate, UIViewControllerTransitioningDelegate, UIGestureRecognizerDelegate, MyCollectionCell {
let transition = CircularAnimation()
var collectionView: UICollectionView!
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(tapEdit(recognizer:)))
func MyCollectionCell() {
let vc = DescriptionViewController()
self.present(vc, animated: true, completion: nil)
}
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.navigationBar.isHidden = true
collectionView.delegate = self
collectionView.dataSource = self
view.backgroundColor = .white
UIApplication.shared.isStatusBarHidden = false
UIApplication.shared.statusBarStyle = .default
view.addSubview(Settings)
view.addSubview(topBar)
view.addSubview(separatorView)
view.addSubview(separatorView2)
Settings.translatesAutoresizingMaskIntoConstraints = false
Settings.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 15).isActive = true
Settings.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
Settings.widthAnchor.constraint(equalToConstant: 50).isActive = true
Settings.heightAnchor.constraint(equalToConstant: 50).isActive = true
separatorView.translatesAutoresizingMaskIntoConstraints = false
separatorView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 40).isActive = true
separatorView.heightAnchor.constraint(equalToConstant: 1).isActive = true
view.addConstraint(NSLayoutConstraint(item: separatorView, attribute: .left, relatedBy: .equal, toItem: Settings, attribute: .right, multiplier: 1, constant: 15))
view.addConstraint(NSLayoutConstraint(item: separatorView, attribute: .right, relatedBy: .equal, toItem: topBar, attribute: .right, multiplier: 1, constant: 0))
separatorView2.translatesAutoresizingMaskIntoConstraints = false
separatorView2.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 40).isActive = true
separatorView2.heightAnchor.constraint(equalToConstant: 1).isActive = true
view.addConstraint(NSLayoutConstraint(item: separatorView2, attribute: .right, relatedBy: .equal, toItem: Settings, attribute: .left, multiplier: 1, constant: -15))
view.addConstraint(NSLayoutConstraint(item: separatorView2, attribute: .left, relatedBy: .equal, toItem: topBar, attribute: .left, multiplier: 1, constant: 0))
topBar.translatesAutoresizingMaskIntoConstraints = false
topBar.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
topBar.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
topBar.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
view.addConstraint(NSLayoutConstraint(item: topBar, attribute: .bottom, relatedBy: .equal, toItem: separatorView, attribute: .top, multiplier: 1, constant: 0))
view.insertSubview(topBar, belowSubview: Settings)
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
let height = (view.frame.width - 16 - 16) * 9/16
layout.sectionInset = UIEdgeInsets(top: 80, left: 0, bottom: 0, right: 0)
layout.itemSize = CGSize(width: view.frame.width, height: height + 16 + 80)
collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
collectionView?.scrollIndicatorInsets = UIEdgeInsetsMake(80, 0, 0, 0)
collectionView.dataSource = self
collectionView.delegate = self
collectionView.register(Cell.self, forCellWithReuseIdentifier: "cellId")
collectionView.backgroundColor = UIColor.clear
collectionView.addGestureRecognizer(tapGesture)
tapGesture.delegate = self
self.view.addSubview(collectionView)
view.insertSubview(collectionView, belowSubview: topBar)
}
let Settings : UIButton = {
let btn = UIButton()
btn.setTitle("Clotho", for: .normal)
btn.setTitleColor(.white, for: .normal)
btn.layer.cornerRadius = 25
btn.backgroundColor = UIColor.rgb(displayP3Red: 255, green: 165, blue: 0)
btn.titleLabel?.font = UIFont(name: "Pacifico-Regular", size: 16)
btn.addTarget(self, action:#selector(settingsTab), for: .touchUpInside)
return btn
}()
let topBar: UIView = {
let bar = UIView()
bar.backgroundColor = .white
return bar
}()
let separatorView: UIView = {
let view = UIView()
view.backgroundColor = UIColor.rgb(displayP3Red: 211, green: 211, blue: 211)
return view
}()
let separatorView2: UIView = {
let view2 = UIView()
view2.backgroundColor = UIColor.rgb(displayP3Red: 211, green: 211, blue: 211)
return view2
}()
@objc func tapEdit(recognizer: UITapGestureRecognizer) {
if recognizer.state == UIGestureRecognizerState.ended {
let tapLocation = recognizer.location(in: self.collectionView)
if let tapIndexPath = self.collectionView.indexPathForItem(at: tapLocation) {
if (self.collectionView.cellForItem(at: tapIndexPath) as? Cell) != nil {
//do what you want to cell here
}
}
}
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 4
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as! Cell
cell.Delegate = self
return cell
}
func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
transition.transitionMode = .present
transition.startingPoint = Settings.center
transition.circleColor = Settings.backgroundColor!
return transition
}
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
transition.transitionMode = .dismiss
transition.startingPoint = Settings.center
transition.circleColor = Settings.backgroundColor!
return transition
}
@objc func settingsTab(){
let secondVC = SettingsViewController()
secondVC.transitioningDelegate = self
secondVC.modalPresentationStyle = UIModalPresentationStyle.custom
self.present(secondVC, animated: true, completion: nil)
}
}
我用var Delegate: MyCollectionCell?在我的牢房里设置了一个protocol
import UIKit
protocol MyCollectionCell {
func MyCollectionCell()
}
class Cell: UICollectionViewCell {
var Delegate: MyCollectionCell?
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
let TapGesture = UITapGestureRecognizer(target: self, action: #selector(Cell.tapEdit(sender:)))
addGestureRecognizer(TapGesture)
TapGesture.delegate = MainFeedViewController()
}
//other setup code...
@objc func tapEdit(sender: UITapGestureRecognizer) {
Delegate?.MyCollectionCell()
}
您实际上没有在任何地方创建集合视图。
这一行：
var collectionView: UICollectionView!
创建一个准备保存集合视图的变量（并且！字符表示您应该在viewDidLoad方法中填充变量），但实际上并没有创建UICollectionView的实例并将其分配给该变量。
因此，当您尝试设置委托和数据源时，集合视图变量仍为零，因此您会收到错误。
您需要实际创建UICollectionView的实例，这也将涉及创建UICollectionViewLayout的实例（或其子类，如UICollectionViewFlowLayout）。
在最基本的层面上，你应该做这样的事情：
let layout = UICollectionViewFlowLayout()
layout.itemSize = CGSize(width: 100, height: 100)
collectionView = UICollectionView(frame: CGRect(x: 0, y: 0, width: 500, height: 500), collectionViewLayout: layout)
当然，您应该调整框架和布局参数以满足您的使用要求。