Swift 代理

swift中代理的使用   

• 首先定義一份協議。

  protocol DetailsViewControllerDelegate: NSObjectProtocol{
      func fetchBackString(str: String)
  }

• 聲明代理屬性

  weak var delegate: DetailsViewControllerDelegate?

• 遵照代理並實現

  class ViewController: DetailsViewControllerDelegate

  let VC = segue.destination as! DetailsViewController
  VC.delegate = self

  //MARK: - DetailsViewControllerDelegate(代理)
  func fetchBackString(str: String) {
      NSLog(str, "")
  }

• 使用

  delegate!.fetchBackString(str: "代理返回數據:\(area.name)")