If you want your circle to increase size from the center, try constructing the circle not by using CGRectMake
but instead use a CGMutablePathRef
, make the path and set the circle's path to the one you created. I have something similar in my game and this worked for me:
SKShapeNode *turnSphere = [[SKShapeNode alloc] init];
CGMutablePathRef path = CGPathCreateMutable();
CGPathAddArc(path, NULL, 0, 0, 30, 0.0, (2 * M_PI), NO);
turnSphere.path = path;
turnSphere.position = CGPointMake(220, 440);
[self addChild:turnSphere];
[turnSphere runAction:[SKAction scaleBy:3 duration:2]];
The circle should now scale up from the center. Hope this works!