以下是發(fā)生異常的代碼

import UIKit
extension NSObject {

    // MARK: - 定義一個類屬性作為閉包容器
    class XYPropertyBlockContainer {

        var viewModelBlock : ViewModelBlock?
        
        var viewMangerInfosBlock : ViewMangerInfosBlock?

        var viewModelInfosBlock : ViewModelInfosBlock?
        
    }
}

問題描述：

Swift項(xiàng)目中再給NSobject類extension中添加類屬性作為閉包容器后狈定，在外界創(chuàng)建給這個閉包容器賦值時颂龙，發(fā)生奔潰，異常內(nèi)容如下：

*** NSForwarding: warning: object 0x17027acc0 of class '_TtCE10MVVMExapleCSo8NSObject24XYPropertyBlockContainer' does not implement methodSignatureForSelector: -- trouble ahead
Unrecognized selector -[_TtCE10MVVMExapleCSo8NSObject24XYPropertyBlockContainer copy]

問題分析：
1.通過異常信息可以發(fā)現(xiàn)是XYPropertyBlockContainer類未實(shí)現(xiàn)copy方法導(dǎo)致的纽什，XYPropertyBlockContainer是我定義的閉包容器類
2.原因這個類我未讓它繼承自NSObject措嵌，當(dāng)我讓其繼承自NSObjcet后，再次運(yùn)行時芦缰，再報(bào)異常reason: '-[_TtCE10MVVMExapleCSo8NSObject24XYPropertyBlockContainer copyWithZone:]: unrecognized selector sent to instance
3.最后讓XYPropertyBlockContainer類繼承自NSObjcet且遵守NSCopying協(xié)議企巢，重寫copy(with zone: NSZone? = nil) -> Any方法解決

解決異常后的代碼

import UIKit

extension NSObject {

    typealias ViewModelBlock = () -> Void
    typealias ViewMangerInfosBlock = () -> Void
    typealias ViewModelInfosBlock = () -> Void
    
    // MARK: - 定義一個類屬性作為block容器
    class XYPropertyBlockContainer: NSObject, NSCopying {
   
        func copy(with zone: NSZone? = nil) -> Any {
            return self
        }
        
        var viewModelBlock : ViewModelBlock?
        var viewMangerInfosBlock : ViewMangerInfosBlock?
        var viewModelInfosBlock : ViewModelInfosBlock?

    }
    
    // MARK: - 關(guān)聯(lián)屬性的key
    private struct RunTimeKey {
        static let blockContainerKey = UnsafeRawPointer(bitPattern: "blockContainerKey".hashValue)
        static let viewMangerDelegateKey = UnsafeRawPointer(bitPattern: "viewMangerDelegate".hashValue)
        static let viewModelDelegateKey = UnsafeRawPointer(bitPattern: "viewModelDelegateKey".hashValue)
        static let xy_viewMangerInfosKey = UnsafeRawPointer(bitPattern: "xy_viewMangerInfosKey".hashValue)
        static let xy_viewModelInfosKey = UnsafeRawPointer(bitPattern: "xy_viewModelInfosKey".hashValue)
        static let xy_mediatorKey = UnsafeRawPointer(bitPattern: "xy_mediatorKey".hashValue)
    }

    /// 閉包容器屬性
    var propertyBlockContainer : XYPropertyBlockContainer? {
        set {
            objc_setAssociatedObject(self, RunTimeKey.blockContainerKey, newValue, .OBJC_ASSOCIATION_COPY_NONATOMIC)
        }
        
        get {
            if let blockContainer = objc_getAssociatedObject(self, RunTimeKey.blockContainerKey) as? XYPropertyBlockContainer {
            
                return blockContainer
            }
            return nil
        }
    }
}

注意：外界給閉包容器中的閉包賦值或者調(diào)用時，需要先創(chuàng)建閉包容器

@IBAction func btnClick(_ sender: Any) {
        // 傳遞事件 通過閉包
        if self.propertyBlockContainer == nil {
            self.propertyBlockContainer = XYPropertyBlockContainer()
            self.propertyBlockContainer?.viewModelInfosBlock = {
                print("1+2")
            }
            self.propertyBlockContainer?.viewModelBlock = {
                print("1+3")
            }
            self.propertyBlockContainer?.viewMangerInfosBlock = {
                print("1+4")
            }
            
            self.propertyBlockContainer?.viewMangerInfosBlock!()
            self.propertyBlockContainer?.viewModelBlock!()
            self.propertyBlockContainer?.viewModelInfosBlock!()
        }