如何符合UICollectionViewDelegate？

Question

我收到一个协议不一致的编译器错误。我遗漏了什么？

extension ViewController: UICollectionViewDataSource {
    func collectionView(collectionView: UICollectionView!, section: Int) -> Int {
        //...
        return 5
    }

    func collectionView(collectionView: UICollectionView!, indexPath: NSIndexPath!) -> UICollectionViewCell! {
        let cell: AnyObject = collectionView.dequeueReusableCellWithReuseIdentifier("turkey", forIndexPath:indexPath)
        return cell as UICollectionViewCell
        //...
    }
}

​

​

swift:45:1: Type 'ViewController' does not conform to protocol 'UICollectionViewDataSource'

Answer 1

尝试删除所有!，因为根据文档，委派没有使用可选选项。

Answer 2

我只是对所有非可选的API进行了剪切/粘贴并重新编译。

显然，这是可行的。

extension ViewController: UICollectionViewDataSource {
    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 5
    }

    // The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell: AnyObject = collectionView.dequeueReusableCellWithReuseIdentifier("turkey", forIndexPath:indexPath)
        return cell as UICollectionViewCell

    }
}