http://petersteinberger.com/blog/2012/pimping-recursivedescription/

PSPDFKitImproveRecursiveDescription.m

// Copyright (c) 2012-2013 Peter Steinberger (http://petersteinberger.com)
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#ifdef DEBUG

///////////////////////////////////////////////////////////////////////////////////////////
#pragma mark - Helper for Swizzling
 
BOOL PSPDFReplaceMethodWithBlock(Class c, SEL origSEL, SEL newSEL, id block) {
    PSPDFAssert(c && origSEL && newSEL && block);
    Method origMethod = class_getInstanceMethod(c, origSEL);
    const char *encoding = method_getTypeEncoding(origMethod);
 
    // Add the new method.
    IMP impl = imp_implementationWithBlock(block);
    if (!class_addMethod(c, newSEL, impl, encoding)) {
        NSLog(@"Failed to add method: %@ on %@", NSStringFromSelector(newSEL), c);
        return NO;
    }else {
        // Ensure the new selector has the same parameters as the existing selector.
        Method newMethod = class_getInstanceMethod(c, newSEL);
        PSPDFAssert(strcmp(method_getTypeEncoding(origMethod), method_getTypeEncoding(newMethod)) == 0, @"Encoding must be the same.");
 
        // If original doesn't implement the method we want to swizzle, create it.
        if (class_addMethod(c, origSEL, method_getImplementation(newMethod), encoding)) {
            class_replaceMethod(c, newSEL, method_getImplementation(origMethod), encoding);
        }else {
            method_exchangeImplementations(origMethod, newMethod);
        }
    }
    return YES;
}

///////////////////////////////////////////////////////////////////////////////////////////
#pragma mark - Improve Description of UIImage/UIImageView

static inline BOOL PSPDFIsVisibleView(__unsafe_unretained UIView *view) {
    BOOL isViewHidden = view.isHidden || view.alpha < 0.01f || CGRectIsEmpty(view.frame);
    return !view || (PSPDFIsVisibleView(view.superview) && !isViewHidden);
}

// Following code patches UIView's description to show the class name of a view controller, if one is attached.
// Will only get compiled for debugging. Use 'po [[UIWindow keyWindow] recursiveDescription]' to invoke.
__attribute__((constructor)) static void PSPDFKitImproveRecursiveDescription(void) {
    @autoreleasepool {
        SEL descriptionSEL = NSSelectorFromString(@"pspdf_description");
        PSPDFReplaceMethodWithBlock(UIView.class, @selector(description), descriptionSEL, ^(id self) {
            NSMutableString *description = [self performSelector:descriptionSEL];
            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) {
                        NSString *origDescription = description;
                        description = [NSMutableString stringWithFormat:@"%dc.[", viewController.childViewControllers.count];
                        for (UIViewController *childViewController in viewController.childViewControllers) {
                            [description appendFormat:@"%@ %p: ", childViewController.class, childViewController];
                        }
                        [description appendFormat:@"] %@", origDescription];
                    }

                    // 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 = @"* OVERLAP! ";
                        }else if (CGRectIsEmpty(childRect)) {
                            warnString = @"* ZERORECT! ";
                        }
                    }
                    description = [NSMutableString stringWithFormat:@"%@%@:%p%@ %@", warnString, viewControllerClassName, viewController, children, description];
                }
            }
            // add marker if view (or a superview) is hidden
            if (!PSPDFIsVisibleView(self)) {
                description = [NSMutableString stringWithFormat:@"XX (%@)", description];
            }
            return description;
        });
    }
}

// Instead of "<UIImage: 0x8b612f0>" we want "<UIImage:0x8b612f0 size:{768, 1001} scale:1 imageOrientation:0>".
// Doesn't use any private API.
__attribute__((constructor)) static void PSPDFKitImproveImageDescription(void) {
    @autoreleasepool {
        SEL descriptionSEL = NSSelectorFromString(@"pspdf_description");
        PSPDFReplaceMethodWithBlock(UIImage.class, @selector(description), descriptionSEL, ^(UIImage *self) {
            NSMutableString *description = [NSMutableString stringWithFormat:@"<%@: %p size:%@", self.class, self, NSStringFromCGSize(self.size)];
            if (self.scale > 1) {
                [description appendFormat:@" scale:%.0f", self.scale];
            }
            if ([self imageOrientation] != UIImageOrientationUp) {
                [description appendFormat:@" imageOrientation:%d", self.imageOrientation];
            }
            [description appendString:@">"];
            return [[description copy] autorelease];
        });
    }
}

// Add image description to UIImageView.
__attribute__((constructor)) static void PSPDFKitImproveImageViewDescription(void) {
    @autoreleasepool {
        SEL descriptionSEL = NSSelectorFromString(@"pspdf_description");
        PSPDFReplaceMethodWithBlock(UIImageView.class, @selector(description), descriptionSEL, ^(UIImageView *self) {
            return [NSString stringWithFormat:@"%@->%@", [self performSelector:descriptionSEL], [self.image description]];
        });
    }
}

#endif

On iOS 7.0, this crashes when executed on a very simple project. Removing the UIImageView (PSPDFKitImproveImageViewDescription) description improvement fixes that up.

(Also, I'd love to have the implementation for PSPDFAssert, I have to strip those out when I sync up to the gist.)