如何根據座標過濾數據？

Question

在我的應用程序中，我有很多位置，並且在當前位置的基礎上，我需要篩選結果並僅顯示5英里半徑內的結果。 有沒有辦法實現這？

感謝，

Answer 1

CLLocation有distanceFromLocation，可以這樣調用

CLLocation dist = [locationA distanceFromLocation:locationB]; 

Answer 2

試試這個功能。這會幫助你。

-(void)distanceBetween{ 


double latitude1 = [merchant.latitude doubleValue]; 
double longitude1 = [merchant.longitude doubleValue]; 

NSUserDefaults *userLocation = [NSUserDefaults standardUserDefaults]; 
float lat = [userLocation floatForKey:@"latitude"]; 
float lon = [userLocation floatForKey:@"longitude"]; 


CLLocation *locA = [[CLLocation alloc] initWithLatitude:latitude1 longitude:longitude1]; 
CLLocation *locB = [[CLLocation alloc] initWithLatitude:lat longitude:lon]; 

CLLocationDistance distanceTo = [locA distanceFromLocation:locB]; 
NSLog(@"locaA is %f", locA); 
NSLog(@"locaB is %f", locB); 
NSLog(@"locdistnace is %f", distanceTo); 
[[self distance] setText:[NSString stringWithFormat:@"%0.2f miles", distanceTo/1609.34]]; 

} 

Answer 3

像這樣的事情應該工作，雖然沒有測試它：

- (NSArray *)filterArrayOfLocations:(NSArray *)array byDistance:(CLLocationDistance)distance toCurrentLocation:(CLLocation*)currentLocation 
{ 
    NSArray *filteredArray = [array filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) { 
     return [currentLocation distanceFromLocation:(CLLocation *)evaluatedObject] < distance; 
    }]]; 
    return filteredArray; 
}