用于比较cocoa/iphone中cllocation对象的nsSortDescriptor

您可以为cllocation编写一个简单的compareToLocation:类别,该类别根据自身和其他cllocation对象之间的距离返回nsorderedAscending、nsorderedDescending或nsorderedName。然后简单地这样做:

NSArray * mySortedDistances = [myDistancesArray sortedArrayUsingSelector:@selector(compareToLocation:)];

编辑:

这样地:

//CLLocation+DistanceComparison.h
static CLLocation * referenceLocation;
@interface CLLocation (DistanceComparison)
- (NSComparisonResult) compareToLocation:(CLLocation *)other;
@end

//CLLocation+DistanceComparison.m
@implementation CLLocation (DistanceComparison)
- (NSComparisonResult) compareToLocation:(CLLocation *)other {
  CLLocationDistance thisDistance = [self distanceFromLocation:referenceLocation];
  CLLocationDistance thatDistance = [other distanceFromLocation:referenceLocation];
  if (thisDistance < thatDistance) { return NSOrderedAscending; }
  if (thisDistance > thatDistance) { return NSOrderedDescending; }
  return NSOrderedSame;
}
@end


//somewhere else in your code
#import CLLocation+DistanceComparison.h
- (void) someMethod {
  //this is your array of CLLocations
  NSArray * distances = ...;
  referenceLocation = myStartingCLLocation;
  NSArray * mySortedDistances = [distances sortedArrayUsingSelector:@selector(compareToLocation:)];
  referenceLocation = nil;
}

为了改进戴夫的回答…

从IOS4开始,您可以使用比较器块,避免使用静态变量和类别:

NSArray *sortedLocations = [self.locations sortedArrayUsingComparator:^NSComparisonResult(CLLocation *obj1, CLLocation *obj2) {
    CLLocationDistance distance1 = [targetLocation distanceFromLocation:loc1];
    CLLocationDistance distance2 = [targetLocation distanceFromLocation:loc2];

    if (distance1 < distance2)
    {
        return NSOrderedAscending;
    }
    else if (distance1 > distance2)
    {
        return NSOrderedDescending;
    }
    else
    {
        return NSOrderedSame;
    }
}];

只需添加到类别响应(这是一种方法),不要忘记您实际上不需要自己做任何数学运算,您可以使用cllocation实例方法:

- (CLLocationDistance)getDistanceFrom:(const CLLocation *)location

获取两个位置对象之间的距离。