关于ios：按距离(纬度和经度)排序表

Sort Table by distance (latitude and longitude)

我正在像这样通过JSON获取值：

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{
id = 1;
latitude ="-23.0002";
longitude ="-43.2438";
name = Vips;
}

{
id = 2;
latitude ="-22.9283";
longitude ="-43.1746";
name = Elegance;
}

...

我需要在表格视图中显示此值，并按与用户位置的距离排序。并且必须始终更新此值。我该怎么办？

displayObject是一个NSMutableArray，我从WS中获取值。
在viewWillappear中，我正在尝试做：

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NSArray *rawData = [NSArray arrayWithArray:displayObject];

rawData = [rawData sortedArrayUsingComparator: ^(id a, id b) {

CLLocationDistance dist_a= [[a objectForKey:@"coordinate"] distanceFromLocation: locAtual];
CLLocationDistance dist_b= [[b objectForKey:@"coordinate"] distanceFromLocation: locAtual];
if ( dist_a < dist_b ) {
return (NSComparisonResult)NSOrderedDescending;
} else if ( dist_a > dist_b) {
return (NSComparisonResult)NSOrderedDescending;
} else {
return (NSComparisonResult)NSOrderedSame;
}
}];

但是它不起作用。我只有纬度和经度。我没有"坐标"。
有人吗？

谢谢！

相关讨论

如果要计算距离，请将其与数组中存储的数据相加，然后根据距离进行排序。

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for (int idx = 0; idx<[displayObject count];idx++) {

NSMutableDictionary *dict = [displayObject[idx] mutableCopy];
CLLocationDegrees latitude = [dict[@"latitude"] doubleValue];
CLLocationDegrees longitude = [dict[@"longitude"] doubleValue];
CLLocation *location = [[CLLocation alloc]initWithLatitude:latitude longitude:longitude];
CLLocationDistance distance = [userLocation distanceFromLocation:location];
//Storing as string since latitude and longitude is also string values
//Since its a dictionary storing as NSNumber is better
dict[@"distance"] = [@(distance) stringValue];

displayObject[idx] = dict;

}

//sorting based on distance
NSSortDescriptor *descriptor = [NSSortDescriptor sortDescriptorWithKey:@"distance" ascending:YES];
[displayObject sortUsingDescriptors:@[descriptor]];

相关讨论

您的比较器错误。请尝试以下方法：

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rawData = [rawData sortedArrayUsingComparator: ^(id a, id b)
{
CLLocation *locationA = [[CLLocation alloc] initWithLatitude:[[a objectForKey:@"latitude"] doubleValue] longitude:[[a objectForKey:@"longitude"] doubleValue]];
CLLocation *locationB = [[CLLocation alloc] initWithLatitude:[[b objectForKey:@"latitude"] doubleValue] longitude:[[b objectForKey:@"longitude"] doubleValue]];

CLLocationDistance dist_a = [locationA distanceFromLocation:currentLocation];
CLLocationDistance dist_b = [locationB distanceFromLocation:currentLocation];

if ( dist_a < dist_b ) {
return (NSComparisonResult)NSOrderedAscending;
} else if ( dist_a > dist_b) {
return (NSComparisonResult)NSOrderedDescending;
} else {
return (NSComparisonResult)NSOrderedSame;
}
}];

首先创建纬度和经度的位置对象：

1 2	CLLocation location = [[CLLocation alloc] initWithLatitude:-23.0002 longitude:-43.2438]; CLLocation userLocation = [[CLLocation alloc] initWithLatitude:-23.0002 longitude:-43.2438];

使用这2个对象，可以轻松地使用以下方法检查距离：

1	-(CLLocationDistance)distanceFromLocation:(const CLLocation *)location

例如：

1	CLLocationDistance dist_a = [locationUser distanceFromLocation:location];