Generate a Graphviz diagram from an Objective-C class inheritance tree. Copy to tree.gv and run `dot -Tpng tree.png tree.gv`

classTreeGraphviz.mm

int numberOfClasses = objc_getClassList(NULL, 0);
Class * classList = (Class *)malloc(numberOfClasses * sizeof(Class));
numberOfClasses = objc_getClassList(classList, numberOfClasses);

NSString * string = @"digraph cluster {\nrankdir=\"LR\"\n";
for (int idx = 0; idx < numberOfClasses; idx++) {
	Class clazz = classList[idx];
	if (some expression to filter results) {

		NSString * str = [NSString stringWithFormat:@"%@ -> %@\n",
			NSStringFromClass(class_getSuperclass(clazz)),
			NSStringFromClass(clazz)];
		string = [string stringByAppendingString:str];
	}
}
free(classList);
string = [string stringByAppendingString:@"}"];
NSLog(@"%@", string);