ios - Swift - 使用委托传递变量
问题描述
我基本上想传递一个数组索引,但我收到一条错误消息,我无法解决问题。
我要访问的索引在我的dropDownView
( didSelectRowAt
) 内。
class dropDownView: UIView, UITableViewDelegate, UITableViewDataSource {
var dropDownOptions = [String]()
var tableView = UITableView()
var delegate : dropDownProtocol!
var selectedWishlistDelegate: selectedWishlistProtocol!
override init(frame: CGRect) {
super.init(frame: frame)
tableView.backgroundColor = UIColor.lightGray
self.backgroundColor = UIColor.lightGray
tableView.delegate = self
tableView.dataSource = self
tableView.translatesAutoresizingMaskIntoConstraints = false
self.addSubview(tableView)
tableView.leftAnchor.constraint(equalTo: self.leftAnchor).isActive = true
tableView.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
tableView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
tableView.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return dropDownOptions.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell()
cell.textLabel?.text = dropDownOptions[indexPath.row]
cell.backgroundColor = UIColor.lightGray
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
self.delegate.dropDownPressed(string: dropDownOptions[indexPath.row])
self.selectedWishlistDelegate.didSelectWishlist(idx: indexPath.row) // fatal error
self.tableView.deselectRow(at: indexPath, animated: true)
}
}
//MARK: Protocols
protocol selectedWishlistProtocol {
func didSelectWishlist(idx: Int)
}
要在我的内部访问它,ExampleViewController
我尝试了这个:
extension ExampleViewController: selectedWishlistProtocol{
func didSelectWishlist(idx: Int) {
self.selectedWishlistIDX = idx
}
}
现在我收到此错误:
线程 1:致命错误:在隐式展开可选值时意外发现 nil
为什么是indexPath.row
nil
??它在delegate
上面的右边工作正常。
可能是初学者的错误,因为我不太适应,delegates
但我很感激每一个帮助:)
更新
我dropDownView
在我的 DropDownBtn`-class 中实例化我的:
class DropDownBtn: UIButton, DropDownProtocol {
func dropDownPressed(string: String) {
self.setTitle(string, for: .normal)
self.dismissDropDown()
}
var dropView = DropDownView()
var height = NSLayoutConstraint()
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = UIColor.lightGray
dropView = DropDownView.init(frame: CGRect.init(x: 0, y: 0, width: 0, height: 0))
dropView.delegate = self
dropView.translatesAutoresizingMaskIntoConstraints = false
}
override func didMoveToSuperview() {
self.superview?.addSubview(dropView)
self.superview?.bringSubviewToFront(dropView)
dropView.topAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
dropView.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
dropView.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
height = dropView.heightAnchor.constraint(equalToConstant: 0)
}
var isOpen = false
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if isOpen == false {
isOpen = true
NSLayoutConstraint.deactivate([self.height])
if self.dropView.tableView.contentSize.height > 150 {
self.height.constant = 150
} else {
self.height.constant = self.dropView.tableView.contentSize.height
}
NSLayoutConstraint.activate([self.height])
UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
self.dropView.layoutIfNeeded()
self.dropView.center.y += self.dropView.frame.height / 2
}, completion: nil)
} else {
isOpen = false
NSLayoutConstraint.deactivate([self.height])
self.height.constant = 0
NSLayoutConstraint.activate([self.height])
UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
self.dropView.center.y -= self.dropView.frame.height / 2
self.dropView.layoutIfNeeded()
}, completion: nil)
}
}
func dismissDropDown() {
isOpen = false
NSLayoutConstraint.deactivate([self.height])
self.height.constant = 0
NSLayoutConstraint.activate([self.height])
UIView.animate(withDuration: 0.2, delay: 0, options: .curveEaseOut, animations: {
self.dropView.center.y -= self.dropView.frame.height / 2
self.dropView.layoutIfNeeded()
}, completion: nil)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
解决方案
确保
var selectedWishlistDelegate:SelectedWishlistProtocol!
不是 nil ,这意味着当您实例化您设置的视图时
let v = DropDownView()
v.selectedWishlistDelegate = // some value
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