swift – 扩展UICollectionViewDataSource协议以添加默认实现

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
    }
}