我正在尝试提取一些代码库以供重用。我的方法是使用Protocol
andProtocol
Extension
而不是 general BaseClass
。
我已经创建了以下一个protocol
和protocol extension
protocol MovieDisplay {
var collectionView: UICollectionView! { get set }
var refreshControl: UIRefreshControl! { get set }
}
extension MovieDisplay where Self: UIViewController {
var refreshControl: UIRefreshControl {
let rc = UIRefreshControl()
rc.backgroundColor = .clear
rc.tintColor = .lightGray
if #available(iOS 10.0, *) {
collectionView.refreshControl = rc
} else {
// Fallback on earlier versions
collectionView.addSubview(rc)
}
return rc
}
}
在采用我这样声明的协议的主类中(使用默认实现refreshcontrol
)
class PopularMovieVC: UIViewController, MovieDisplay {
@IBOutlet weak var collectionView: UICollectionView!
}
问题是涉及的功能refreshcontrol
不起作用。只有当我refreshcontrol
在主类中显式声明变量并将扩展转换为函数并在主类中调用它时,它才有效,如下所示:
func setupRefreshControl() {
refreshControl.backgroundColor = .clear
refreshControl.tintColor = .lightGray
if #available(iOS 10.0, *) {
collectionView.refreshControl = refreshControl
} else {
// Fallback on earlier versions
collectionView.addSubview(refreshControl)
}
}
如何正确配置protocol
和protocol extension
默认实现?