使用 NSObject 的 Swift 2.1 委托

Posted 2023-02-26

【中文标题】使用 NSObject 的 Swift 2.1 委托

【英文标题】：Swift 2.1 Delegation with NSObject

【发布时间】：2016-02-01 00:56:25

【问题描述】：

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“扫描仪”时出错了。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?)

【参考方案1】：

第一种方式：

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

我不认为在 init 中使用委托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