ios 存储字典数组 ios字典取值崩溃

对字典和数组进行下列操作时会产生crash：

对于字典来说：

查询时，key=nil 或者 key=null 时都能正常运行

插入时，，key=nil 或者 key=null 都会crash 

对于数组来说

index越界会crash

添加对象为nil时会crash

NSDictionary@{@"key":@"value"};
NSStringobjectForKey:nil];
objectForKey:[NSNullnull]];
NSMutableDictionarycopy];
objectForKey:nil];
objectForKey:[NSNullnull]];
    
objectForKey:[NSNullnull]];
    
//    [mutDic setObject:@"123" forKey:nil];crash
//    [mutDic setObject:nil forKey:@"123"];crash
//    [mutDic setObject:[NSNull null] forKey:@"key"];crash
//    [mutDic setObject:@"value" forKey:[NSNull null]];crash
    
//    [mutDic removeObjectForKey:nil]; //crash
//    [mutDic removeObjectForKey:[NSNull null]];//crash
//
NSArray@[@(1),@(2),@(3)];
//    value = [arr objectAtIndex:4];//crash
NSMutableArraymutableCopy];
    
//    [mutArr insertObject:@(5) atIndex:5];//crash
//    [mutArr removeObjectAtIndex:5]; //crash
//    [mutArr replaceObjectAtIndex:5 withObject:@"5"];//crash
//    [mutArr insertObject:nil atIndex:0]; //crash
    
insertObject:[NSNullnull] atIndex:0];
replaceObjectAtIndex:0withObject:[NSNullnull]];