相关疑难解决方法(0)

我正在尝试创建一个协议,包含使用UIImagePickerController的过程,使其在我的应用程序中更流线型.我基本上有这样的事情:

public protocol MediaAccessor : UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    func mediaCaptured(title: String, fileData: NSData, fileType: String)
}

和一个扩展,它完成了请求权限和处理委托方法的所有繁重工作:

public extension MediaAccessor where Self : UIViewController {
    public func captureMedia() {
        //All sorts of checks for picker authorization
        let picker = UIImagePickerController()
        picker.delegate = self
        self.presentViewController(picker, animated: true, completion: nil)
    }

    func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {
        //implementation of the delegate in extension
        //even though everything compiles, this method is not called on picker completion
    }
} …

我想创建一个继承UICollectionViewDataSource和使用协议扩展的协议,以提供所需UICollectionViewDataSource方法的默认实现.但是,当我尝试声明符合此协议的类时,编译器会说Type 'MyClass' does not conform to protocol UICollectionViewDataSource'.

protocol MyDataSource : UICollectionViewDataSource {
    var values: [String] { get }
}

extension MyDataSource {
    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = UICollectionViewCell() // TODO: dequeue
        // TODO: configure cell ...
        return cell
    }

    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return self.values.count
    }
}

class MyClass : NSObject, MyDataSource {
    var values = [String]()
}

我也尝试将扩展名声明为以下内容,但仍然收到相同的编译器错误:

extension UICollectionViewDataSource …