我已经建立了基本的CellAssociation协议。
但是,我添加到协议中的任何内容都会得到:
"Type 'FooTableView' does not conform to protocol 'Cell Association'"
Xcode似乎给了我一些提示:
"Multiple maching functions named 'register(cellClass:forCellReuseIdentifier:)' with type '(AnyClass?, String) -> ()' (aka '(Optional<AnyObject.Type>, String) -> ()')"
和..
"Rename to 'register(cellClass:forCellReuseIdentifier:)' to satisfy this requirement"
但是,看来我的注册函数就是这样命名的。
这是CellAssociation(TableView.swift)
import UIKit
protocol CellAssociation {
associatedtype Cell: UITableViewCell
func register()
func register(cellClass: AnyClass?, forCellReuseIdentifier: String)
func dequeueReusableCell(for: IndexPath) -> Cell
func dequeueReusableCell(withIdentifier: String, for: IndexPath) -> UITableViewCell
}
extension CellAssociation {
func register() {
register(cellClass: Cell.self, forCellReuseIdentifier: String(describing: Cell.self))
}
func dequeueReusableCell(for indexPath: IndexPath) -> Cell {
return dequeueReusableCell(withIdentifier: String(describing: Cell.self), for: indexPath) as! Cell
}
}
这是一个试图遵守该协议的TableView:
import UIKit
class LineupDraftSortMenuTableView: UITableView, CellAssociation {
typealias Cell = LineupDraftSortMenuCell
init() {
super.init(frame: CGRect.zero, style: .plain)
setup()
}
required convenience init?(coder: NSCoder) {
self.init()
}
func setup() {
rowHeight = 40
separatorStyle = .none
backgroundColor = UIColor.clear
register()
}
}
此类将引发错误:
"Type 'LineupDraftSortMenuTableView' does not conform to protocol 'CellAssociation'"
和LineupDraftSortMenuCell
import UIKit
class LineupDraftSortMenuCell: UITableViewCell {
let optionLabel = DraftboardLabel()
let iconCheck = UIImageView()
let borderView = UIView()
var selectedOption: Bool = false { didSet { toggleIconCheck() } }
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
setup()
}
required convenience init?(coder: NSCoder) {
self.init()
}
func setup() {
addSubviews()
setupSubviews()
addConstraints()
}
func addSubviews() {
contentView.addSubview(optionLabel)
contentView.addSubview(iconCheck)
contentView.addSubview(borderView)
}
func setupSubviews() {
backgroundColor = UIColor.clear
contentView.backgroundColor = UIColor.clear
selectionStyle = .none
optionLabel.font = UIFont.openSans(weight: .Semibold, size: 9)
optionLabel.textColor = UIColor.white
optionLabel.letterSpacing = 0.5
iconCheck.image = UIImage(named: "icon-check")
iconCheck.contentMode = .scaleAspectFit
iconCheck.isHidden = !selectedOption
borderView.backgroundColor = UIColor(0x5c656f)
}
func addConstraints() {
let viewConstraints: [NSLayoutConstraint] = [
optionLabel.leftRancor.constraintEqualToRancor(rancor: contentView.leftRancor, constant: 20),
optionLabel.centerYRancor.constraintEqualToRancor(rancor: contentView.centerYRancor),
iconCheck.widthRancor.constraintEqualToConstant(constant: 12),
iconCheck.heightRancor.constraintEqualToConstant(constant: 10),
iconCheck.centerYRancor.constraintEqualToRancor(rancor: contentView.centerYRancor),
iconCheck.rightRancor.constraintEqualToRancor(rancor: contentView.rightRancor, constant: -20),
borderView.leftRancor.constraintEqualToRancor(rancor: contentView.leftRancor, constant: 10),
borderView.rightRancor.constraintEqualToRancor(rancor: contentView.rightRancor, constant: -10),
borderView.bottomRancor.constraintEqualToRancor(rancor: contentView.bottomRancor),
borderView.heightRancor.constraintEqualToConstant(constant: 1),
]
optionLabel.translatesAutoresizingMaskIntoConstraints = false
iconCheck.translatesAutoresizingMaskIntoConstraints = false
borderView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate(viewConstraints)
}
func toggleIconCheck() {
iconCheck.isHidden = !selectedOption
}
}
答案 0 :(得分:2)
实际上,最近,我几乎遇到了您可以参考的问题(Swift: Conforming to protocols using default values)。
因此,请参考此内容,这是您的代码的修改版本。
protocol CellAssociation {
associatedtype Cell: UITableViewCell
func register(cellClass: AnyClass?, forCellReuseIdentifier: String)
func dequeueReusableCell(withIdentifier: String, forIndexPath indexPath: IndexPath) -> UITableViewCell
}
extension CellAssociation {
func register(cellClass: AnyClass? = Cell.self, forCellReuseIdentifier: String = String(describing: Cell.self)) {
return register(cellClass: cellClass, forCellReuseIdentifier: forCellReuseIdentifier)
}
func dequeueReusableCell(withIdentifier: String = String(describing: Cell.self), forIndexPath indexPath: IndexPath) -> UITableViewCell {
return dequeueReusableCell(withIdentifier: withIdentifier, forIndexPath: indexPath)
}
}
我要做的是,我通过了默认值,因为您为此创建了一个不同的方法,并在extension
中进行了确认。现在,它将确认protocol
。让我知道,如果您还有其他疑问或问题。
答案 1 :(得分:2)
您的协议具有以下要求:
protocol CellAssociation {
func register(cellClass: AnyClass?, forCellReuseIdentifier: String)
}
但是您的表视图子类LineupDraftSortMenuTableView永远不会实现该方法。因此它不符合协议。
也许您假设该函数声明与UITableView已经实现的某些东西匹配,所以UITableView子类可以符合您的协议而无需显式实现它。但是事实并非如此。 UITableView已经拥有的方法是:
func register(_ cellClass: AnyClass?, forCellReuseIdentifier identifier: String)
下划线有很大的不同!
因此,如果您重写协议及其扩展名以匹配UITableView已实现的内容,则代码将编译,如下所示:
protocol CellAssociation {
associatedtype Cell: UITableViewCell
func register()
func register(_ cellClass: AnyClass?, forCellReuseIdentifier: String)
func dequeueReusableCell(for: IndexPath) -> Cell
func dequeueReusableCell(withIdentifier: String, for: IndexPath) -> UITableViewCell
}
extension CellAssociation {
func register() {
register(Cell.self, forCellReuseIdentifier: String(describing: Cell.self))
}
func dequeueReusableCell(for indexPath: IndexPath) -> Cell {
return dequeueReusableCell(withIdentifier: String(describing: Cell.self), for: indexPath) as! Cell
}
}
一旦您说了这一点,就可以合法地说:
class LineupDraftSortMenuTableView: UITableView, CellAssociation {
// ...
}