如何测试两个CLLocations的相等性 [英] How do I test the equality of two CLLocations

问题描述

我遇到了isEqual问题:

I'm having a problem with isEqual:

代码:

 if (currentAnchor isEqual:currentBusiness.getCllLocation))
    {
        do a;
    }
    else
    {
        do b;
    }

currentanchor和currentbusiness.getCllocation是位置

currentanchor and currentbusiness.getCllocation are locations

但是如果它们相同，为什么要调用函数b?我的代码有问题吗?

But if they are the same, why is function b called? Is something wrong with my code?

推荐答案

我假定这两个对象都是基于getClLocation名称的CLLocation类型.

I assume both of these objects are of type CLLocation, based on the name of getClLocation.

CLLocation对其isEqual:方法的功能没有任何规范，因此它很可能只是继承了NSObject的实现，该实现只是比较对象的指针.如果您有两个具有相同数据的不同对象，则该isEqual:实现将返回NO.而且，如果您有两个不同的对象，只是位置略有不同，那么它们肯定是不相等的.

CLLocation doesn't have any specification on what its isEqual: method does, so it's likely just inheriting the implementation of NSObject, which simply compares the pointers of the objects. If you've got two distinct objects with identical data, that isEqual: implementation would return NO. And if you've got two distinct objects with just a slight variation in location, they definitely would not be equal.

比较位置对象时，您可能不希望isEqual:.相反，您可能想在CLLocation上使用distanceFromLocation:方法.这样的事情会更好:

You probably don't want isEqual: when comparing location objects. Rather, you probably want to use the distanceFromLocation: method on CLLocation. Something like this would be better:

CLLocationDistance distanceThreshold = 2.0; // in meters
if ([currentAnchor distanceFromLocation:currentBusiness.getCllLocation] < distanceThreshold)
{
  do a;
}
else
{
  do b;
}

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