Calling an unusual method in initWithSize - objective-c

Question

I've found code for making a rope in my Sprite Kit game. I'll post it below. Problem is, the method header is very long & has a syntax that I'm unable to call upon in my initWithSize method. I tried writing [self addRopeJointItems]; but to no avail. Yes. I am new to objective-c. Hope someone can help out.
Code:
+(void)addRopeJointItems:(CGPoint)leftStartPosition countJointElements:(int)countJointElements game:(SKScene*)game
{
int itemJointWidth = 25;
//Left Physics Anchor
SKSpriteNode * leftAnchor = [SKSpriteNode spriteNodeWithColor:[SKColor clearColor] size:CGSizeMake(1, 1)];
leftAnchor.position = CGPointMake(leftStartPosition.x, leftStartPosition.y);
//leftAnchor.size = CGSizeMake(1, 1);
leftAnchor.zPosition = 2;
leftAnchor.physicsBody = [SKPhysicsBody
bodyWithRectangleOfSize:
leftAnchor.size];
leftAnchor.physicsBody.affectedByGravity = false;
leftAnchor.physicsBody.mass = 99999999999;
[game addChild:leftAnchor];
//add RopeElements
for (int i=0; i<countJointElements; i++)
{
SKSpriteNode * item = [SKSpriteNode spriteNodeWithImageNamed:#"rope_ring.png"];
item.name = [NSString stringWithFormat:#"ropeitem_%d", i];
item.position = CGPointMake(leftStartPosition.x + (i*itemJointWidth) + itemJointWidth/2, leftStartPosition.y+60);
item.size = CGSizeMake(itemJointWidth + 5, 5);
item.zPosition = 2;
item.physicsBody = [SKPhysicsBody
bodyWithRectangleOfSize:
item.size];
item.physicsBody.categoryBitMask = kNilOptions;
[game addChild:item];
//Add Joint to the element before
SKPhysicsBody* bodyA;
if (i == 0)
{
bodyA = leftAnchor.physicsBody;
}
else
{
bodyA = [game childNodeWithName:[NSString stringWithFormat:#"ropeitem_%d", i-1]].physicsBody;
}
SKPhysicsJointPin* joint = [SKPhysicsJointPin jointWithBodyA:bodyA bodyB:item.physicsBody anchor:CGPointMake((item.position.x - item.size.width/2) + 5, item.position.y)];
[game.physicsWorld addJoint:joint];
}
//Right Physics Anchor
SKSpriteNode * rightAnchor = [SKSpriteNode spriteNodeWithColor:[SKColor clearColor] size:CGSizeMake(1, 1)];
rightAnchor.position = CGPointMake((leftStartPosition.x + (countJointElements*itemJointWidth)),
leftStartPosition.y+60);
//rightAnchor.size = CGSizeMake(1, 1);
rightAnchor.zPosition = 2;
rightAnchor.physicsBody = [SKPhysicsBody
bodyWithRectangleOfSize:
rightAnchor.size];
rightAnchor.physicsBody.affectedByGravity = false;
rightAnchor.physicsBody.mass = 99999999999;
[game addChild:rightAnchor];
//Add the Last Joint
SKPhysicsJointPin* jointLast = [SKPhysicsJointPin jointWithBodyA:[game childNodeWithName:[NSString stringWithFormat:#"ropeitem_%d", countJointElements - 1]].physicsBody
bodyB:rightAnchor.physicsBody
anchor:rightAnchor.position];
[game.physicsWorld addJoint:jointLast];
}

Answer 1

You can do two things here:-
1) Either change your method to instance method with prefix (-). If you want call as instance method with self
-(void)addRopeJointItems:(CGPoint)leftStartPosition countJointElements:(int)countJointElements game:(SKScene*)game
2)Or follow #Andrey Chernukha comments as
[ClassName addRopeJointItems:leftStartPosition countJointElements:elements game:game];