Sorting Distance in UITableview based on current location - ios

Question

How can i sort the array based on distance from current location and show in tableview .when i use below code for sorting am not getting any proper results ,am getting the array with random distance.can any one guide me for solve this issue
-(void)sort_distance{
// Determine distance between current location and geofence location
[distance_array removeAllObjects];
NSMutableDictionary *dict=[[NSMutableDictionary alloc] init];
CLLocation *pinLocation;
CLLocation *userLocation;
for (int i=0; i<[self.geofences count]; i++) {
//dict =[self.geofences objectAtIndex:i];
CLLocationDegrees firstLat = [self.currentLatitude doubleValue];
CLLocationDegrees firstLong = [self.currentLongitude doubleValue];
CLLocationDegrees secondLat = [[[self.geofences objectAtIndex:i] objectForKey:#"lat"] doubleValue];
CLLocationDegrees secondLong = [[[self.geofences objectAtIndex:i] objectForKey:#"lon"] doubleValue];
pinLocation = [[CLLocation alloc]
initWithLatitude:secondLat
longitude:secondLong];
userLocation = [[CLLocation alloc]
initWithLatitude:firstLat
longitude:firstLong];
CLLocationDistance distance = [pinLocation distanceFromLocation:userLocation]/1000;
//current distance is NSNumber
CLLocationDistance kilometers = distance /1000;
// or you can also use this..
distanceString = [[NSString alloc] initWithFormat: #"%.1f Km", kilometers];
NSLog(#"sa: %#", distanceString);
[distance_array addObject:distanceString];
[dict setObject:[NSNumber numberWithDouble:distance] forKey:#"newdistance"];
}
NSLog(#"distance array: %#", distance_array);
// Sorting the Geofence-Location depends on distance from current location
NSSortDescriptor * sort = [[NSSortDescriptor alloc] initWithKey:#"newdistance" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObject:sort];
sortedArray = [self.geofences sortedArrayUsingDescriptors:sortDescriptors];
}
My out put is
distance array: (
"0.2 Km",
"0.4 Km",
"0.2 Km",
"0.6 Km",
"0.7 Km",
"1.0 Km",
"0.3 Km"
)
Thanks in Advance,
Chandu.

Answer 1

-(void)sort_distance{
// Determine distance between current location and geofence location
[distance_array removeAllObjects];
NSMutableDictionary *dict=[[NSMutableDictionary alloc] init];
CLLocation *pinLocation;
CLLocation *userLocation;
for (int i=0; i<[self.geofences count]; i++) {
//dict =[self.geofences objectAtIndex:i];
CLLocationDegrees firstLat = [self.currentLatitude doubleValue];
CLLocationDegrees firstLong = [self.currentLongitude doubleValue];
CLLocationDegrees secondLat = [[[self.geofences objectAtIndex:i] objectForKey:#"lat"] doubleValue];
CLLocationDegrees secondLong = [[[self.geofences objectAtIndex:i] objectForKey:#"lon"] doubleValue];
pinLocation = [[CLLocation alloc]
initWithLatitude:secondLat
longitude:secondLong];
userLocation = [[CLLocation alloc]
initWithLatitude:firstLat
longitude:firstLong];
CLLocationDistance distance = [pinLocation distanceFromLocation:userLocation]/1000;
//current distance is NSNumber
CLLocationDistance kilometers = distance /1000;
// or you can also use this..
distanceString = [[NSString alloc] initWithFormat: #"%.1f km", kilometers];
NSLog(#"sa: %#", distanceString);
[distance_array addObject:distanceString];
[dict setObject:[NSNumber numberWithDouble:distance] forKey:#"newdistance"];
}
NSLog(#"distance array: %#", distance_array);
// Sorting the Geofence-Location depends on distance from current location
sortedArray = [distance_array sortedArrayUsingSelector:#selector(compare:)];
NSLog(#"%#",sortedArray);
}

Answer 2

CLLocationDistance is double type, while you are saving it as integer type. So you will loose some precision. Instead use `[NSNumber numberWithDouble:].
This will sort in ascending order, for descending order return NSOrderedAscending in place of NSOrderedDescending and vice-versa.
-(CLLocationDistance )distanceOfCurrentPosition:(CLLocation *)userLocation WithPosition:(NSDictionary *)postition{
CLLocationDegrees secondLat = [postition[#"lat"] doubleValue];
CLLocationDegrees secondLong = [postition[#"lon"] doubleValue];
CLLocation *pinLocation = [[CLLocation alloc]
initWithLatitude:secondLat
longitude:secondLong];
CLLocationDistance distance = [pinLocation distanceFromLocation:userLocation]/1000;
CLLocationDistance kilometers = distance /1000;
return kilometers;
}
-(void)sort_distance{
CLLocationDegrees firstLat = [self.currentLatitude doubleValue];
CLLocationDegrees firstLong = [self.currentLongitude doubleValue];
CLLocation *userLocation = [[CLLocation alloc]
initWithLatitude:firstLat
longitude:firstLong];
[_geofences sortUsingComparator:^NSComparisonResult(NSDictionary *position1, NSDictionary *position2) {
CLLocationDistance distanceWithPosition1 = [self distanceOfCurrentPosition:userLocation WithPosition:position1];
CLLocationDistance distanceWithPosition2 = [self distanceOfCurrentPosition:userLocation WithPosition:position2];
if (distanceWithPosition1> distanceWithPosition2) {
return NSOrderedDescending;
}else if(distanceWithPosition2 > distanceWithPosition1){
return NSOrderedAscending;
}else{
return NSOrderedSame;
}
}];
NSLog(#"Order :%#",_geofences);
}

Answer 3

Try these for sort your array
-(NSArray *)sortArray:(NSArray *)arrayForSort forKey:(NSString *)key
{
return [arrayForSort sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
if([obj1 isKindOfClass:[NSDictionary class]] && [obj2 isKindOfClass:[NSDictionary class]])
return [[obj1 objectForKey:key] compare:[obj2 objectForKey:key]];
return NSOrderedSame;
}];
}
Just call it your case
self.geofences = [self sortArray:self.geofences forKey:#"newdistance"];
Have a nice day :)