pre iOS 4.3

PSPDFKitImproveRecursiveDescription.m

# You need #import <objc/runtime.h>

#ifdef DEBUG

void pspdf_swizzle(Class c, SEL orig, SEL new) {
    Method origMethod = class_getInstanceMethod(c, orig);
    Method newMethod = class_getInstanceMethod(c, new);
    if(class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod))) {
        class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    }else {
        method_exchangeImplementations(origMethod, newMethod);
    }
}

NSString* pspdf_customViewDescription(id _self, SEL _cmd) {
        SEL customViewDescriptionSEL = NSSelectorFromString(@"pspdf_customViewDescription");
        NSString *description = [_self performSelector:customViewDescriptionSEL];
        SEL viewDelegateSEL = NSSelectorFromString([NSString stringWithFormat:@"%@ewDelegate", @"_vi"]); // pr. API
        if ([_self respondsToSelector:viewDelegateSEL]) {
            UIViewController *viewController = [_self performSelector:viewDelegateSEL];
            NSString *viewControllerClassName = NSStringFromClass([viewController class]);
            if ([viewControllerClassName length]) {
                NSString *children = @""; // iterate over childViewControllers
                if ([viewController respondsToSelector:@selector(childViewControllers)] && [viewController.childViewControllers count]) {
                    description = [NSString stringWithFormat:@"%d children:[ ", [viewController.childViewControllers count]];
                    for (UIViewController *childViewController in viewController.childViewControllers) {
                        description = [NSString stringWithFormat:@"%@%@:%p ", description, NSStringFromClass([childViewController class]), childViewController];
                    }
                    description = [description stringByAppendingString:@"]"];
                }

                // check if the frame of a childViewController is bigger than the one of a parentViewController. (usually this is a bug)
                NSString *warnString = @"";
                if (viewController && viewController.parentViewController && [viewController isViewLoaded] && [viewController.parentViewController isViewLoaded]) {
                    CGRect parentRect = viewController.parentViewController.view.bounds;
                    CGRect childRect = viewController.view.frame;

                    if (parentRect.size.width < childRect.origin.x + childRect.size.width ||
                        parentRect.size.height < childRect.origin.y + childRect.size.height) {
                        warnString = @"OVERLAPPING PARENT! ";
                    }
                }

                description = [NSString stringWithFormat:@"%@'%@:%p'%@ %@", warnString, viewControllerClassName, viewController, children, description];
            }
        }
        return description;
}


__attribute__((constructor)) static void PSPDFKitImproveRecursiveDescription(void) {
    // Following code patches UIView's description to show the classname of an an view controller, if one is attached.
    // Will only get compiled for debugging. Use 'po [[UIWindow keyWindow] recursiveDescription]' to invoke.

    SEL customViewDescriptionSEL = NSSelectorFromString(@"pspdf_customViewDescription");
    class_addMethod([UIView class], customViewDescriptionSEL, (IMP)pspdf_customViewDescription, "@@:");
    pspdf_swizzle([UIView class], @selector(description), customViewDescriptionSEL);
}
#endif