数据库中查询，两个经纬度之间的距离代码
时间：2021-07-01 10:21:17
帮助过：65人阅读
radians(
double degrees)
{
return degrees * M_PI /
180.0;
}
- (
void)testDistance
{
FMDatabase *db =
[FMDatabase databaseWithPath:_writableDBPath];
if (!
[db open]) {
return;
}
[db makeFunctionNamed:@"distance" maximumArguments:
4 withBlock:^(sqlite3_context *context,
int argc, sqlite3_value **
argv) {
double values[
4];
// get the double values for the four arguments
for (
int i =
0; i <
4; i++
) {
int dataType =
sqlite3_value_numeric_type(argv[i]);
if (dataType == SQLITE_INTEGER || dataType ==
SQLITE_FLOAT) {
values[i] =
sqlite3_value_double(argv[i]);
} else {
sqlite3_result_null(context);
return;
}
}
// let‘s give those values meaningful variable names
double lat = radians(values[
0]);
double lng = radians(values[
1]);
double lat2 = radians(values[
2]);
double lng2 = radians(values[
3]);
// calculate the distance
double result =
6371.393 * acos(cos(lat2) * cos(lat) * cos(lng2 - lng) + sin(lat2) *
sin(lat));
sqlite3_result_double(context, result);
}];
int rowCount =
0;
FMResultSet *rs = [db executeQuery:
@"SELECT *,distance(lat,lng,34.27344,108.95996) AS distance FROM hotel WHERE cityId = 10 AND lat > 33.27344 AND lat < 35.27344 AND lng > 107.95996 AND lng < 109.95996 ORDER BY distance ASC LIMIT 10"];
while ([rs next]) {
rowCount++
;
NSLog(@"Does %@,%@ ", [rs stringForColumnIndex:
1],[rs stringForColumn:
@"distance"]);
}
}
数据库中查询，两个经纬度之间的距离代码
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