如何在Swift中列出所有实现给定协议的类?假设我们有一个例子:
protocol Animal {
func speak()
}
class Cat:Animal {
func speak() {
print("meow")
}
}
class Dog: Animal {
func speak() {
print("Av Av!")
}
}
class Horse: Animal {
func speak() {
print("Hurrrr")
}
}
这是我的当前(无法编译的)方法:
func getClassesImplementingProtocol(p: Protocol) -> [AnyClass] {
let classes = objc_getClassList()
var ret = [AnyClass]()
for cls in classes {
if class_conformsToProtocol(cls, p) {
ret.append(cls)
}
}
return ret
}
func objc_getClassList() -> [AnyClass] {
let expectedClassCount = objc_getClassList(nil, 0)
let allClasses = UnsafeMutablePointer<AnyClass?>.alloc(Int(expectedClassCount))
let autoreleasingAllClasses = AutoreleasingUnsafeMutablePointer<AnyClass?>(allClasses)
let actualClassCount:Int32 = objc_getClassList(autoreleasingAllClasses, expectedClassCount)
var classes = [AnyClass]()
for i in 0 ..< actualClassCount {
if let currentClass: AnyClass = allClasses[Int(i)] {
classes.append(currentClass)
}
}
allClasses.dealloc(Int(expectedClassCount))
return classes
}
但是调用以下任一语句:
getClassesImplementingProtocol(Animal.Protocol)
或者
getClassesImplementingProtocol(Animal)
或者
getClassesImplementingProtocol(Animal.self)
都会导致 Xcode 报错:“无法将类型 (Animal.Protocol).Type 转换为预期的参数类型 'Protocol'。”
是否有人成功解决了这个问题?