Traverse the class hierarchy from base to all descendants

In an iOS app, I write that I want to traverse the class hierarchy to make an inventory of all subclasses. I intend to use each type of subclass as a key - via NSStringForClass()

- in the dictionary.

My motivation is to be able to automatically detect all variants of a base class so that I can call methods associated with that class. For division of labor reasons, I prefer not to use the override method here.

Is it possible to make such a detour? How it works?


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1 answer

Here's an example. This method returns all subclasses descended from the class you are posting to.

@interface NSObject (Debugging)

+ (NSArray *) allSubclasses;


@implementation NSObject (Debugging)

+ (NSArray *) allSubclasses
    Class myClass = [self class];
    NSMutableArray *mySubclasses = [NSMutableArray array];

    unsigned int numOfClasses;
    Class *classes = objc_copyClassList(&numOfClasses);
    for (unsigned int ci = 0; ci < numOfClasses; ci++) {
        // Replace the code in this loop to limit the result to immediate subclasses:
        // Class superClass = class_getSuperclass(classes[ci]);
        // if (superClass == myClass)
        //  [mySubclasses addObject: classes[ci]];
        Class superClass = classes[ci];
        do {
            superClass = class_getSuperclass(superClass);
        } while (superClass && superClass != myClass);

        if (superClass)
            [mySubclasses addObject: classes[ci]];

    return mySubclasses;



Change it as needed, make recursive calls, etc.



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