如何从一个方法返回多个值

Question

I have -(CLLocationCoordinate2D) method, I want to return multiple locations from that method (those locations are using in another method) my method looks like this,

-(CLLocationCoordinate2D) addressLocation{
 - --------
 ----------
 return location;
 }

is it possible to return multiple locations (I mean return location1, return location2. . ..)?? please help me thanks

Answer 1

CLLocationCoordinate2D is not an object so they can not just be added to an array and returned. Since they are structs there are a few options,

1. malloc an array the old fashion way and copy the struct data into the array
2. malloc a new struct pointer, copy the data, then store the pointer in an NSValue
3. Create a class that has the same properties as the fields of the struct, and add that to an array

Option 1 and 2 require additional memory management as to when to free the data so avoid those. Option 3 is good and it just so happens MapKit offers the class CLLocation . Here is an example of 2 coordinates.

-(NSArray*) addressLocations
{
    CLLocationCoordinate2D coord1 = CLLocationCoordinate2DMake(1.00, 1.00);
    CLLocationCoordinate2D coord2 = CLLocationCoordinate2DMake(2.00, 2.00);

    CLLocation *loc1 = [[CLLocation alloc] initWithLatitude:coord1.latitude longitude:coord1.longitude];
    CLLocation *loc2 = [[CLLocation alloc] initWithLatitude:coord2.latitude longitude:coord2.longitude];

    NSArray *array = [NSArray arrayWithObjects:loc1, loc2, nil];

    [loc1 release];
    [loc2 release];

    return array;
}

Answer 2

Add your location objects to an array and return the array instead. eg

-(NSArray*) addressLocation{
   ...  // Set your locations up
   NSArray *array = [NSArray arrayWithObjects:location1, location2, nil];
   ... // Do any additional processing and return array.
}