Question

I’m currently pulling info from an sql DB where the ‘cachedDist’ column is set as a double. However when I pull it into my app and create my array I turn it into an String and the sort will obviously be off, 18.15 will come before 2.15. How do I fix that in my code so it will sort distance as a Double and not a String?

In Bar object.

NSString *cachedDist
@property(nonatomic,copy) NSString *cachedDist;

---

@synthesize cachedDist;

---

My while loop in the View Controller.

while (sqlite3_step(sqlStatement)==SQLITE_ROW) {
            Bar * bar = [[Bar alloc] init];
            bar.barName = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,1)];
            bar.barAddress = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,2)];
            bar.barCity = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 3)];
            bar.barState = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 4)];
            bar.barZip = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 5)];
            bar.barLat = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 8)];
            bar.barLong = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 9)];

            if (currentLoc == nil) {
                NSLog(@"current location is nil %@", currentLoc);
            }else{

            CLLocation *barLocation = [[CLLocation alloc] initWithLatitude:[bar.barLat doubleValue] longitude:[bar.barLong doubleValue]];
            bar.cachedDist = [NSNumber numberWithDouble:[currentLoc distanceFromLocation: barLocation]/1000];

            [thebars addObject:bar];

            }

My sorting

NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:@"cachedDist"  ascending:YES];
sortedArray = [thebars sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]];

return sortedArray;

Answer 1

NSString has a method doubleValue to make this quite simple:

double cachedDistance = [cachedDistanceString doubleValue];

which you can use in a custom comparator for your sorting, or else make the property an NSNumber or double to make sorting that much easier. (I’m not sure how you are sorting…)

edit:

I re-evaluated your code, and now it looks like we are going from a double to a string to a double… we can cut out the middle-man, so to speak.

In your @prototype section, change the @property:

// @property(nonatomic,copy) NSString *cachedDist; // old way
@property(nonatomic) double cachedDist;

then assign it like this:

bar.cachedDistance = [currentLoc distanceFromLocation: barLocation]/1000;

and remove the lines which create a string from the distance (which is actually just a double).

Alternatively, if you want to be more object oriented, you can (should?) use NSNumber objects:

@property(nonatomic,copy) NSNumber *cachedDist;
...
bar.cachedDistance = [NSNumber numberWithDouble:[currentLoc distanceFromLocation: barLocation]/1000];