Swift 类别：“无法将类型的值转换为预期的参数类型 'AnyObject!'

Question

我正在尝试将 Objective C 中的类别转换为 swift。我什至对 Objective C 类别都不太熟悉，现在我收到错误："Cannot convert value of type 'SelectionBlock!' to expected argument type of 'AnyObject!'"，而且我不确定从这里去哪里。

import Foundation
import MapKit
import ObjectiveC

var AssociatedObjectHandle: UInt8 = 0

extension MKPointAnnotation {

    typealias SelectionBlock = () -> Void

    var selectionBlock: SelectionBlock! {
        get {
            return objc_getAssociatedObject(self, &AssociatedObjectHandle) as! SelectionBlock
        }
        set(selectionBlock) {
            objc_setAssociatedObject(self, &AssociatedObjectHandle, selectionBlock, objc_AssociationPolicy.OBJC_ASSOCIATION_COPY)
        }
    }

}

Answer 1

Caroline，尝试强制将 selectionBlock 放入 AnyObject

extension MKPointAnnotation {

    typealias SelectionBlock = () -> Void

    var selectionBlock: SelectionBlock! {
        get {
            return objc_getAssociatedObject(self, &AssociatedObjectHandle) as! SelectionBlock
        }
        set(selectionBlock) {
            objc_setAssociatedObject(self, &AssociatedObjectHandle, selectionBlock as! AnyObject, objc_AssociationPolicy.OBJC_ASSOCIATION_COPY)
        }
    }

}