自iOS8起，NullSafe在UIKit / Webkit / UIWebViewPDF / UIWebView / UIWebDocumentView /上崩溃

Question

Okay so this iOS8 is starting to cause a lot of problems, and this is one of them.

I'm using the NullSafe library (that you can find on github) that basically returns nil instead of an exception when parsing something empty.

Now when NullSafe is working, it just browse all the classes (from every framework/bundle/kit in your project ). I'm not really confident in the understanding on why this Nullsafe library does that, but it does it, and it crashes now.

When debugging, the class being checked when crashing varies, but we can never find it anywhere in the apple doc or the bundles... So my conclusion is :

It appears that NullSafe is trying to browse classes that don't exist

• I can't really get rid of NullSafe, or at least i'd like to try not to for the time being.
• It always appears to crash on view related classes.
• They never seem to exist when we look for them.

Does any of you use NullSafe or know anything about it so we could try to go forward?

Answer 1

After contacting Nick (maker of Nullsafe )i've seen my issues go away. He just gave me the latest version, 1.2.1.

Here is the complete Nullsafe.m file :

//
//  NullSafe.m
//
//  Version 1.2.1
//
//  Created by Nick Lockwood on 19/12/2012.
//  Copyright 2012 Charcoal Design
//
//  Distributed under the permissive zlib License
//  Get the latest version from here:
//
//  https://github.com/nicklockwood/NullSafe
//
//  This software is provided 'as-is', without any express or implied
//  warranty.  In no event will the authors be held liable for any damages
//  arising from the use of this software.
//
//  Permission is granted to anyone to use this software for any purpose,
//  including commercial applications, and to alter it and redistribute it
//  freely, subject to the following restrictions:
//
//  1. The origin of this software must not be misrepresented; you must not
//  claim that you wrote the original software. If you use this software
//  in a product, an acknowledgment in the product documentation would be
//  appreciated but is not required.
//
//  2. Altered source versions must be plainly marked as such, and must not be
//  misrepresented as being the original software.
//
//  3. This notice may not be removed or altered from any source distribution.
//

#import <objc/runtime.h>
#import <Foundation/Foundation.h>


#ifndef NULLSAFE_ENABLED
#define NULLSAFE_ENABLED 1
#endif


#pragma GCC diagnostic ignored "-Wgnu-conditional-omitted-operand"


@implementation NSNull (NullSafe)

#if NULLSAFE_ENABLED

- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector
{
    @synchronized([self class])
    {
        //look up method signature
        NSMethodSignature *signature = [super methodSignatureForSelector:selector];
        if (!signature)
        {
            //not supported by NSNull, search other classes
            static NSMutableArray *classList = nil;
            static NSMutableDictionary *signatureCache = nil;
            if (signatureCache == nil)
            {
                classList = [[NSMutableArray alloc] init];
                signatureCache = [[NSMutableDictionary alloc] init];

                //get class list
                int numClasses = objc_getClassList(NULL, 0);
                Class *classes = (Class *)malloc(sizeof(Class) * (unsigned long)numClasses);
                numClasses = objc_getClassList(classes, numClasses);

                //add to list for checking
                NSMutableSet *excluded = [NSMutableSet set];
                for (int i = 0; i < numClasses; i++)
                {
                    //determine if class has a superclass
                    Class someClass = classes[i];
                    Class superclass = class_getSuperclass(someClass);
                    while (superclass)
                    {
                        if (superclass == [NSObject class])
                        {
                            [classList addObject:someClass];
                        }
                        Class next = class_getSuperclass(superclass);
                        [excluded addObject:NSStringFromClass(superclass)];
                        superclass = next;
                    }
                }

                //remove all classes that have subclasses
                for (Class someClass in [classList reverseObjectEnumerator])
                {
                    if ([excluded containsObject:NSStringFromClass(someClass)])
                    {
                        [classList removeObject:someClass];
                    }
                }

                //free class list
                free(classes);
            }

            //check implementation cache first
            NSString *selectorString = NSStringFromSelector(selector);
            signature = [signatureCache objectForKey:selectorString];
            if (!signature)
            {
                //find implementation
                for (Class someClass in classList)
                {
                    if ([someClass instancesRespondToSelector:selector])
                    {
                        signature = [someClass instanceMethodSignatureForSelector:selector];
                        break;
                    }
                }

                //cache for next time
                [signatureCache setObject:signature ?: [NSNull null] forKey:selectorString];
            }
            else if ([signature isKindOfClass:[NSNull class]])
            {
                signature = nil;
            }
        }
        return signature;
    }
}

- (void)forwardInvocation:(NSInvocation *)invocation
{
    [invocation invokeWithTarget:nil];
}

#endif

@end

Hope this helps :)