iOS的圓和線在雪碧包

Question

我想畫一個圓圈，從圓圈中心，這也是兩倍長圓的半徑

我的輸出繪圖與線旁邊的圓圈有一條線。

- (void)setupMainBall { 
    mainBall = [self makeMainBall]; 
    mainBall.position = CGPointMake(self.size.width/2, self.size.height/2); 
    mainBall.zPosition = 3; 

    [self addChild:mainBall]; 
    [mainBall addChild:[self makeCanon]]; 
} 

-(SKShapeNode *)makeMainBall { 
    SKShapeNode *theMainBall = [[SKShapeNode alloc] init]; 
    CGMutablePathRef myPath = CGPathCreateMutable(); 
    CGPathAddArc(myPath, NULL, 0, 0, 10, 0, M_PI*2, YES); 

    theMainBall.fillColor = [SKColor blueColor]; 
    theMainBall.path = myPath; 
    theMainBall.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:theMainBall.frame.size.width/2]; 

    return theMainBall; 
} 

-(SKSpriteNode *)makeCanon { 
    canon = [SKSpriteNode spriteNodeWithColor:[SKColor blackColor] size:CGSizeMake(3, 20)]; 
    canon.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:canon.frame.size]; 
    return canon; 
} 

Answer 1

嘗試：

SKSpriteNode *canon = [self makeCannon]; 
[mainBall addChild:canon]; 
canon.position = CGPointMake(mainBall.size.width/2, mainBall.size.width /2);