如何在Swift中构建和使用我自己的数据源协议

Question

我想为用户提供一个自定义视图组件库的标头视图的选项。

所以我想遵循UITableViewDataSource协议并尝试实现这样的事情。

//customview.swift

protocol CustomViewDatasource: class {
   func heightForHeader(in view: CustomView) -> CGFloat
   func headerView(in view: CustomView) -> UIView
}
class CustomView: UIView {
   weak var dataSource: CustomViewDatasource?
   /// How can I draw the custom header view passing by dataSource?
}

//viewcontroller.swift

extension ViewController: CustomViewDatasource {
  ...
  func headerView(in view: CustomView) -> UIView {
    let headerView = UIView()
    headerView.backgroundColor = .green
    return headerView
  }
  func heightForHeader(in view: CustomView) -> CGFloat {
    return 150
  }
}

如何绘制通过DataSource通过的标头视图？

我不知道。我感谢任何帮助。

谢谢。

Answer 1

通过在您的CustomView中调用。

class CustomView: UIView {
    private let headerViewTag = 42
    weak var dataSource: CustomViewDatasource? {
        didSet {
            updateHeaderView()
        }
    }
    private func updateHeaderView() {
        // remove the old one
        viewWithTag(headerViewTag)?.removeFromSuperview()
        // ask for customized data
        let headerView = dataSource?.headerView(in: self) ?? defaultHeaderView()
        let headerViewHeight = dataSource?.heightForHeader(in: self) ?? 100
        headerView?.translatesAutoresizingMaskIntoConstraints = false
        headerView?.tag = headerViewTag
        if let headerView = headerView {
            addSubview(headerView)
            // set your constraints
        }
    }
    private func defaultHeaderView() -> UIView {
        // default header view's implementation here
    }
}