我有一个相当大的应用程序,它有很多集合视图.大多数集合视图都具有相同的数据源和流布局代表(相同的大小,边距等)的实现.我正在尝试创建一个提供UICollectionViewDataSource和UICollectionViewDelegateFlowLayout的默认实现的协议.这是我的代码.
protocol TiledCollectionView{}
extension UICollectionViewDataSource where Self: TiledCollectionView{
//default implementation of the 3 methods to load the data ...
}
extension UICollectionViewDelegateFlowLayout where Self: TiledCollectionView {
//default implementation for layout methods to set default margins etc...
}
class MyViewController: UIViewController,TiledCollectionView,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout{
// the rest of the required logic for view controller
// here I Don't implement any CollectionView methods since I have provided the default implementation already
}
问题是,编译器抱怨MyViewController不符合UICollectionViewDataSource.这不应该是这种情况,因为我清楚地说,如果类型是TiledCollectionView,则添加默认实现.
有人可以帮忙吗？
我知道这不完全是你问的,我试过 – 它没用.现在寻找可能的答案,因为有类似的情况.但我可以为您提供如何选择如何在自定义协议中隐藏委托/数据源实现的所有逻辑.
class CollectionViewProtocolHandler: NSObject,UICollectionViewDelegate,UICollectionViewDataSource {
func collectionView(collectionView: UICollectionView,numberOfItemsInSection section: Int) -> Int {
return 0
}
func collectionView(collectionView: UICollectionView,cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
return UICollectionViewCell() // only for test
}
}
protocol CollectionViewProtocol {
var handler: CollectionViewProtocolHandler! {get set}
mutating func useProtocolForCollectionView(collectionView: UICollectionView)
}
extension CollectionViewProtocol {
mutating func useProtocolForCollectionView(collectionView: UICollectionView) {
handler = CollectionViewProtocolHandler()
collectionView.delegate = handler
collectionView.dataSource = handler
}
}
class ViewController: UIViewController,CollectionViewProtocol {
var handler: CollectionViewProtocolHandler! // CollectionViewProtocol convenience
override func viewDidLoad() {
super.viewDidLoad()
let collectionView = UICollectionView(frame: view.bounds,collectionViewLayout: UICollectionViewFlowLayout())
collectionView.backgroundColor = .redColor()
view.addSubview(collectionView)
var reference = self
reference.useProtocolForCollectionView(collectionView) // for initialize protocol
}
}