获取 5 个最近的注释 MKMapKit答案

【问题标题】：Get 5 Nearest Annotations MKMapKit获取 5 个最近的注释 MKMapKit
【发布时间】：2011-03-07 22:43:32
【问题描述】：

我正在使用 MKMapKit 来获取 100 公里半径内的最近位置。但是我想知道如何对数组进行排序，以便在数组顶部给我最近的五个注释。

我当前的代码是：

    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]];
        }
    }

【问题讨论】：

标签： iphone objective-c xcode ios4 sorting

【解决方案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;
    }
}

然后您可以使用选择器进行排序：

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

【讨论】：

【解决方案2】：

如果您使用的是 iOS4，您可以使用块来简化此操作：

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];

【讨论】：