ios - 自 iOS8 以来，NullSafe 在 UIKit/Webkit/UIWebViewPDF/UIWebView/UIWebDocumentView/... 上崩溃

Question

好吧，这个 iOS8 开始引起很多问题，这就是其中之一。

我正在使用 NullSafe 库(您可以在 github 上找到)，在解析空内容时它基本上返回 nil 而不是异常。

现在，当 NullSafe 工作时，它只是浏览所有类(来自项目中的每个框架/ bundle /套件)。我不太有信心理解为什么这个 Nullsafe 库会这样做，但它确实做到了，而且现在崩溃了。

调试时，崩溃时检查的类有所不同，但我们永远无法在苹果文档或 bundle 中的任何位置找到它......所以我的结论是:

NullSafe 似乎正在尝试浏览不存在的类

• 我无法真正摆脱 NullSafe，或者至少我想尝试不这样做暂时到。
• 它总是出现与 View 相关的崩溃类。
• 当我们寻找它们时，它们似乎从未存在过。

你们中有人使用 NullSafe 或了解它，以便我们可以尝试继续吗？

Answer 1

联系 Nick(Nullsafe 的制造商)后，我发现我的问题消失了。他刚刚给了我最新版本，1.2.1。

这是完整的 Nullsafe.m 文件:

//
//  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

希望这有帮助:)