addObjectsFromArray will not add them as new objects - ios

Question

My problem is when I copy an array with objects, it seems that if i change the copied array, the original array changes as well. Below is a simplified version of my code.
I have an array of objects
#interface TimesViewController (){
NSMutableArray *route1;
}
I fill these objects up in my ViewDidLoad method
route1 = [[NSMutableArray alloc] init];
while (sqlite3_step(statement) == SQLITE_ROW) {
StopsOnRoutes *stopOnRoutes = [[StopsOnRoutes alloc] init];
[stopOnRoutes setStart_time:p_time];
[stopOnRoutes setStart_route_id:p_route];
[stopOnRoutes setStart_stop_id:p_stop];
[stopOnRoutes setStop_time:c_time];
[stopOnRoutes setStop_route_id:c_route];
[stopOnRoutes setStop_stop_id:c_stop];
[stopOnRoutes calc];
[route1 addObject:stopOnRoutes];
}
BUT when I try to copy route1 and make a few changes, they change both in route1 and amTimes
NSMutableArray *amTimes = [[NSMutableArray alloc] init];
[amTimes addObjectsFromArray:route1];
for(int i = 0; i<amTimes.count; i++){
[[amTimes objectAtIndex:i] setStop_time:[[amTimes objectAtIndex:i] stop_time]-86400];
[[amTimes objectAtIndex:i] setStart_time:[[amTimes objectAtIndex:i] start_time]-86400];
}
How can I copy route1 to amTimes, so if I change an object in AM times, it won't change in route1.

Answer 1

The way arrays work they simply hold references (pointers) to the objects in the array. Therefore when you add objects, it does not create a new object and point to it, it simply points to that very same object. What you want to do is referred to as a deep copy array, which involves coping each object inside the array.
Which is what happens when you use
- (instancetype)initWithArray:(NSArray *)array copyItems:(BOOL)flag
Each object in the array is send a copyWithZone, you can implement copyWithZone in each of the objects you want to add to your array, and then do
[myArray addObject[myObject copy]];
Or you can also use
[[NSArray alloc] initWithArray:otherArray copyItems:YES] //You need to implement copyWithZone in the items you want to copy.
This will give you the result that you want.

Answer 2

You need to have your StopOnRoutes class implement the NSCopying protocol and the copyWithZone: method. This method needs to create a copy of self.
Then you can do this:
NSMutableArray *amTimes = [[NSMutableArray alloc] init];
for (StopOnRoutes *obj in route1) {
[amTimes addObject:[obj copy]];
}

Answer 3

Container objects don't contain copies of the objects that are added to them, they contain pointers to the objects. If you add the same object to 2 arrays, it is a member of both arrays.
If you want to create an array of copies, you need to do several things:
You need to implement the NSCopying protocol for the objects in your array so you can copy them.
Then you'd need to create a new mutable array with room for the same number of elements as the first array, loop through the first array, copy each item, and add it to the second array.
If your array contains only standard system objects that support NSCopying then your work is simpler. If your array contains different kinds of custom objects or complex custom objects then you might have more work to do.

Answer 4

Try using setArray: i.e.[amTimes setArray:route1];