NSSet -member检查NSValue的相等性 [英] NSSet -member to check equality of NSValue

问题描述

我有一个 NSSet ，包含数千个 NSValue 对象（包装 CGPoints ）。我想很快找到 NSSet 中是否存在给定的 CGPoint 值。在我看来， NSSet 的成员：方法可以在这里完成工作，除了它检查是否相等使用 isEqual：。 NSValue 对象使用 isEqualToValue：，所以当我执行代码时：

I have a NSSet containing many thousands of NSValue objects (wrapping CGPoints). I would like to very quickly find if a given CGPoint value exists in the NSSet. It seems to me that the member: method of an NSSet might do the job here, except that it checks for equality using isEqual:. NSValue objects use isEqualToValue:, and so when I execute the code:

[mySet member:valueToCheck];

它实际上导致Xcode崩溃。

it actually causes Xcode to crash.

1）是否有某种方法可以使用自定义相等检查使其适用于 NSValue 对象？

1) Is there some way to use a custom equality check to make this work for NSValue objects?

2 ）这是否是最好的方法（即首先是成员：足够快）？场景是我有一个 NSSet ，其中包含大量代表屏幕（iPad）像素的点。后来我需要以每秒数千点的速度轰击那一组，看看它们是否存在于集合中。我的方法似乎很难实现这一点。我想创建类似于一个巨大的二维位数组的东西，每个索引代表一个屏幕上的像素。一旦我知道我正在测试的那一点，我就可以直接跳到阵列中的那一点并检查1或0 ......这听起来好不好？

2) Is this even the best approach (i.e. is member: quick enough in the first place)? The scenario is that I have a NSSet containing a large number of points representing pixels on the screen (iPad). Later on I need to bombard that set with many thousands of points per second to see if they exist in the set. My approach seems crude for achieving this. I thought about creating something like a huge 2-dimensional bit array, with each index representing a pixel on screen. Once I know the point I'm testing for, I can just jump straight to that point in the array and check for a 1 or 0... does this sound better or worse?

谢谢

推荐答案

你能把它变成一个简单的可重复的案例吗？例如，我刚试过：

Can you get this to a simple reproducible case? For example, I just tried:

NSValue *v = [NSValue valueWithCGPoint:CGPointMake(1, 1)];
NSSet *s = [NSSet setWithObject:v];
NSLog(@"%@", [s member:[NSValue valueWithCGPoint:CGPointMake(1, 1)]]);

但它运作正常。

编辑

-isEqual：不是问题：

NSValue *v1 = [NSValue valueWithPoint:NSMakePoint(1, 1)];
NSValue *v2 = [NSValue valueWithPoint:NSMakePoint(1, 1)];
NSLog(@"%d", [v1 isEqual:v2]); //logs "1"

-hash 不是问题：

NSLog(@"%d", ([v1 hash] == [v2 hash])); //logs "1"

它们是不同的对象：

NSLog(@"%d", (v1 != v2)); //logs "1"

问题在于您的代码。尝试清理和重建。

The problem is in your code. Try cleaning and rebuilding.

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