Container类型crash防护（Container）

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Container crash 产生原因

Container 类型的crash 指的是容器类的crash，常见的有NSArray／NSMutableArray／NSDictionary／NSMutableDictionary／NSCache的crash。 一些常见的越界，插入nil，等错误操作均会导致此类crash发生。 由于产生的原因比较简单，就不展开来描述了。

该类crash虽然比较容易排查，但是其在app crash概率总比还是挺高，所以有必要对其进行防护。

Container crash 防护方案

Container crash 类型的防护方案也比较简单，针对于NSArray／NSMutableArray／NSDictionary／NSMutableDictionary／NSCache的一些常用的会导致崩溃的API进行method swizzling，然后在swizzle的新方法中加入一些条件限制和判断，从而让这些API变的安全如下：

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[self swizzlingInstance:objc_getClass("__NSPlaceholderDictionary") orginalMethod:@selector(initWithObjects:forKeys:count:) replaceMethod:NSSelectorFromString(@"qiye_initWithObjects:forKeys:count:")];
       
       [self swizzlingInstance:objc_getClass("__NSPlaceholderDictionary") orginalMethod:@selector(dictionaryWithObjects:forKeys:count:) replaceMethod:NSSelectorFromString(@"qiye_dictionaryWithObjects:forKeys:count:")];
       
       [self swizzlingInstance:objc_getClass("__NSDictionaryM") orginalMethod:@selector(setObject:forKey:) replaceMethod:NSSelectorFromString(@"qiye_setObject:forKey:")];
       
       [self swizzlingInstance:objc_getClass("__NSPlaceholderArray") orginalMethod:@selector(initWithObjects:count:) replaceMethod:NSSelectorFromString(@"qiye_initWithObjects:count:")];
       
       [self swizzlingInstance:objc_getClass("__NSArrayI") orginalMethod:@selector(objectAtIndex:) replaceMethod:NSSelectorFromString(@"qiye_objectAtIndex:")];
       
       [self swizzlingInstance:objc_getClass("__NSArrayM") orginalMethod:@selector(addObject:) replaceMethod:NSSelectorFromString(@"qiye_addObject:")];
       
       [self swizzlingInstance:objc_getClass("__NSArrayM") orginalMethod:@selector(insertObject:atIndex:) replaceMethod:NSSelectorFromString(@"qiye_insertObject:atIndex:")];
       
       [self swizzlingInstance:objc_getClass("__NSArrayM") orginalMethod:@selector(objectAtIndex:) replaceMethod:NSSelectorFromString(@"qiye_objectAtIndex:")];
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+(BOOL)swizzlingInstance:(Class)clz orginalMethod:(SEL)originalSelector  replaceMethod:(SEL)replaceSelector{
    Method original = class_getInstanceMethod(clz, originalSelector);
    Method replace = class_getInstanceMethod(clz, replaceSelector);
    BOOL didAddMethod =
    class_addMethod(clz,
                    originalSelector,
                    method_getImplementation(replace),
                    method_getTypeEncoding(replace));
    
    if (didAddMethod) {
        class_replaceMethod(clz,
                            replaceSelector,
                            method_getImplementation(original),
                            method_getTypeEncoding(original));
    } else {
        method_exchangeImplementations(original, replace);
    }
    return YES;
}