ios 通过runtime 获取类对象的所有子类

oc写法

//获取指定类的子类
- (NSArray *)findSubClass:(Class)defaultClass

{
    
    //注册类的总数
    int count = objc_getClassList(NULL,0);
    
    //创建一个数组，其中包含给定对象
    NSMutableArray * array = [NSMutableArray arrayWithObject:defaultClass];
    
    //获取所有已注册的类
    Class *classes = (Class *)malloc(sizeof(Class) * count);
    
    objc_getClassList(classes, count);
    
    //遍历
    for (int i = 0; i < count; i++) {
        
        if (defaultClass == class_getSuperclass(classes[i])) {
            
            [array addObject:classes[i]];
            
        }
        
    }
    
    free(classes);
    return array;
    
}

swift 写法

 fileprivate class func performOnce(){
        
        //注册类的总数
        let count = Int(objc_getClassList(nil, 0))
        
        //分配空间 
        let classes = UnsafeMutablePointer.allocate(capacity: count)
        
        //转类型
        let autoreleaseClasses = AutoreleasingUnsafeMutablePointer(classes)
        
        //获取所有的类
        objc_getClassList(autoreleaseClasses, Int32(count))
        
        
        for index in 0..