Not casting properly?

Question

I'm following this tutorial. And I keep getting this casting error. I've imported the Obstacle.h file in the shown class (MainScene.m). I have no idea what I'm doing wrong

 - (void)spawnNewObstacle {
     CCNode *previousObstacle = [_obstacles lastObject];
     CGFloat previousObstacleXPosition = previousObstacle.position.x;

     if (!previousObstacle) {
         // this is the first obstacle
         previousObstacleXPosition = firstObstaclePosition;
     }

     Obstacle *obstacle = (Obstacle *)[CCBReader load:@"Obstacle"];
     obstacle.position = ccp(previousObstacleXPosition + distanceBetweenObstacles, 0);
     [obstacle setUpRandomPosition];
     [_physicsNode addChild:obstacle];
     [_obstacles addObject:obstacle];
 }

Error:

-[CCNode setUpRandomPosition]: unrecognized selector sent to instance 0x9a88a30
2014-04-20 10:51:28.046 FlappyFlyl[2104:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CCNode setUpRandomPosition]: unrecognized selector sent to instance 0x9a88a30'

What makes you think that casting changes the class of an object?? All it does is tell the compiler to consider the type to be the one specified. — Hot Licks, Apr 20 '14 at 15:01
afaik obstacle is the first child of the node returned by ccbreader load — CodeSmile, Apr 20 '14 at 15:47
Sorry, I haven't programmed in a while and I've forgotten a lot of these concepts. What would you suggest I do to fix it? The example runs fine with the same code — stumped, Apr 20 '14 at 15:49
write a correct CCNode class that has the code you expect it to have — Daij-Djan, Apr 20 '14 at 17:22
@LearnCocos2D that is only the case for `loadAsScene`. A regular `load` should return the SpriteBuilder root node. — Ben-G, Apr 20 '14 at 22:37

score 1 · Answer 1 · answered Apr 20 '14 at 22:39

1

Likely you didn't set the custom class of your root node in "Obstacle.ccb" in SpriteBuilder correctly. That's why your "Obstacle.ccb" root node is a CCNode and not an Obstacle object.

answered Apr 20 '14 at 22:39

Ben-G

4,996
27
33

score 0 · Answer 2 · answered Apr 20 '14 at 17:48

The obstacle variable does not hold an object of type Obstacle. Instead it holds an object of type CCNode. CCNode does not have a method named -setUpRandomPosition, so you get a runtime error. In Objective-C, casting is a no-op. It doesn't do anything except helping the reader of your code see the intent of the person who wrote the code.

In this regard Objective-C differs from languages like C++ or Java. Objective-C has an object system that is similar to the programming language "Smalltalk".

Not casting properly?

2 Answers2