ios - objc_copyClassList : crash EXC_BAD_INSTRUCTION after update to iOS 13. 4/XCode 11.4

Question

更新到 iOS 13.4/XCode 11.4 后

这段代码

func getSubclassInfos() -> [ClassInfo] {
    let superObject = CityModel.self
    let superClassInfo = ClassInfo(superObject)

    var subclassList = [ClassInfo]()
    var count = UInt32(0)
    guard let classList = objc_copyClassList(&count) else {
        return subclassList
    }
    for i in 0..<Int(count) {
        let clazz = classList[i] // Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
        if let classInfo = ClassInfo(classList[i]),
            let superclassInfo = classInfo.superclassInfo,
            superclassInfo == superClassInfo
        {
            subclassList.append(classInfo)
        }
    }

    return subclassList
}

在线崩溃 let clazz = classList[i]与 EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)在模拟器中。

这行不在我的原始代码中。在这里显示下标崩溃而不是 ClassInfo(...)
知道我能做些什么吗？

(代码的灵感来自 List all subclasses of one class )

Answer 1

刚注意到:classList完全是用词不当。返回的结果类型为 AutoreleasingUnsafeMutablePointer<AnyClass>? .将其转换为 UnsafeBufferPointer<AnyClass>首先，然后进行处理:

func getSubclassInfos() -> [ClassInfo] {
    let superObject = CityModel.self
    let superClassInfo = ClassInfo(superObject)

    var count = UInt32(0)
    guard let classListPointer = objc_copyClassList(&count) else { return [] }

    return UnsafeBufferPointer(start: classListPointer, count: Int(count))
        .map(ClassInfo.init)
        .filter { $0 == superClassInfo }
}