Swift 2.1 使用 NSObject 委托

Question

我正在处理下面的示例并收到一条错误消息：

Cannot convert value of type 'NSObject -> () -> CentralViewController   
to expected argument type 'TransferServiceDelegate?'

我正在尝试完成委托，但在我尝试初始化时出现错误 'scanner'。任何帮助将不胜感激..谢谢！:

import UIKit
import Foundation


protocol TransferServiceScannerDelegate: NSObjectProtocol {
    func didStartScan()
    func didStopScan()
    func didTransferData(data: NSData?)
}

class TransferServiceScanner: NSObject{
    weak var delegate: TransferServiceScannerDelegate?

    init(delegate: TransferServiceScannerDelegate?) {
        self.delegate = delegate
        super.init()
    }

}

class CentralViewController: UIViewController,
TransferServiceScannerDelegate {

   *let scanner: TransferServiceScanner = TransferServiceScanner(self)*

   func didStartScan(){}
   func didStopScan(){}
   func didTransferData(data: NSData?){}

}

Answer 1

第一种方式：

lazy var scanner: TransferServiceScanner = {
        let scanner = TransferServiceScanner(delegate: self)
        return scanner
    }()

我认为在init中使用委托不是一个好方法和必要的，你也可以这样做：

class TransferServiceScanner: NSObject{
    weak var delegate: TransferServiceScannerDelegate?

    init(delegate: TransferServiceScannerDelegate?) {
        self.delegate = delegate
        super.init()
    }

    override init() {
        super.init()
    }
}

class CentralViewController: UIViewController,
TransferServiceScannerDelegate {

    var scanner: TransferServiceScanner = TransferServiceScanner()

    func didStartScan(){}
    func didStopScan(){}
    func didTransferData(data: NSData?){}

    override func viewDidLoad() {
        super.viewDidLoad()
        scanner.delegate = self
    }
}

Swift 2.1 使用 NSObject 委托

Swift 2.1 Delegation with NSObject

delegation

ios9

swift2