Question

我正在使用MKMapKit来获取100公里范围内最近的位置。但是我想知道如何对数组进行排序，以便在数组顶部给出最接近的五个注释。

我目前的代码是：

    CLLocation *currentlocation = [[CLLocation alloc] initWithLatitude:annotation.coordinate.latitude longitude:annotation.coordinate.longitude];
    annotation.distanceToTarget = [currentlocation distanceFromLocation:usrlocation];
    annotation.title = [dict objectForKey:@"name"];
    annotation.subtitle = [NSString stringWithFormat:@"%@, %@, %@",[dict objectForKey:@"street"],[dict objectForKey:@"county"], [dict objectForKey:@"postcode"]];
    annotation.subtitle = [annotation.subtitle stringByReplacingOccurrencesOfString:@", ," withString:@""];
    if (annotation.distanceToTarget/1000 < 168) {
        abc++;
        NSLog(@"Distances Lower Than 168: %i", abc);
        [storesLessThan100KAway addObject:annotation];
        NSLog(@"Stores Count: %i", [storesLessThan100KAway count]);
    }
    for (int i = 0; i <= 5; i++) {
        //NSLog(@"Stores Count For Loop: %i", [storesLessThan100KAway count]);
        if ([storesLessThan100KAway count] > 5) {
            [mapView addAnnotation:[storesLessThan100KAway objectAtIndex:i]];
        }
    }

Answer 1

为注释编写自己的比较方法：

- (NSComparisonResult)compare:(Annotation *)otherAnnotation {
    if (self.distanceToTarget > otherAnnotation.distanceToTarget) {
        return NSOrderedDescending;
    } else if (self.distanceToTarget < otherAnnotation.distanceToTarget) {
        return NSOrderedAscending;
    } else {
        return NSOrderedSame;
    }
}

然后你可以使用选择器进行排序：

NSArray *sortedArray = [storesLessThan100KAway sortedArrayUsingSelector:@selector(compare:)];

Answer 2

如果您使用的是iOS4，则可以使用块来更轻松地实现这一目标：

NSComparator compareAnnotations = ^(Annotation *obj1, Annotation *obj2) {
    if (obj1.distanceToTarget > obj2.distanceToTarget) {
        return NSOrderedDescending;
    } else if (obj1.distanceToTarget < obj2.distanceToTarget) {
        return NSOrderedAscending;
    } else {
        return NSOrderedSame;
    }
};

NSArray *sortedArray = [storesLessThan100KAway sortedArrayUsingComparator:compareAnnotations];

获取5个最近的注释MKMapKit

2 个答案: