同步推笔试坑录

1.下列输出是什么?(个人尝试bad_access。。。有人解答吗？）

    NSString *text = @"info";
    memset((__bridge void *)(text), 0, text.length-1);
    NSString *myString = [NSString stringWithFormat:@"info"];
    NSLog(@"%@",myString);

2.ios c函数如何hook?（不懂）

3.写一个NSString类的实现

+ (id)initWithCString:(const char *)nullTerminatedCString encoding:(NSStringEncoding)encoding;

+ (id) stringWithCString: (const char*)nullTerminatedCString 
            encoding: (NSStringEncoding)encoding
{
  NSString  *obj;
  obj = [self allocWithZone: NSDefaultMallocZone()];
  obj = [obj initWithCString: nullTerminatedCString encoding: encoding];
  return AUTORELEASE(obj);
}

4.oc冒泡排序

for (int i = 0; i<[arg count]; i++) 
 for (int j=i+1; j<[arg count]; j++){
            int a = [[arg objectAtIndex:i] intValue];
            int b = [[arg objectAtIndex:j] intValue];
            if (a > b)
            {
                [arg replaceObjectAtIndex:i withObject:[NSString stringWithFormat:@"%d",b]];
                [arg replaceObjectAtIndex:j withObject:[NSString stringWithFormat:@"%d",a]];
            }
   }