ios - 与顶部和底部碰撞但不与侧面碰撞？ (iOS 8)

Question

我制作了一个球从屏幕上弹起的简单效果。它只适用于顶部和底部边缘，但我不知道为什么。此外，当我在 iOS 7 SpriteKit 模板中的 initwithsize 方法中尝试这段代码时，它起作用了。这是错误还是什么？

#import "GameScene.h"

@implementation GameScene

-(void)didMoveToView:(SKView *)view {
    self.backgroundColor = [SKColor whiteColor];
    SKSpriteNode *ball =[SKSpriteNode spriteNodeWithImageNamed:@"ball"];
    ball.position =CGPointMake(self.frame.size.width/2, self.frame.size.height/2);
    ball.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:ball.frame.size.width/2];
    self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];
    self.physicsWorld.gravity = CGVectorMake(0, 0);
    CGVector impulse =     CGVectorMake(20,20);
    [self addChild:ball];
    
    [ball.physicsBody applyImpulse:  impulse];
    
    ball.physicsBody.restitution = 1;
    ball.physicsBody.friction = 0;
    ball.physicsBody.linearDamping = 0;
    
  /* 
   SKSpriteNode *wall =[SKSpriteNode spriteNodeWithImageNamed:@"wall"];
   
   SKSpriteNode *bar =[SKSpriteNode spriteNodeWithImageNamed:@"bar"];

   wall.position= CGPointMake(self.frame.size.width/2, 103);
    bar.position = CGPointMake(self.frame.size.width/2,  (wall.frame.size.height));
    [self addChild:wall];
    [self addChild:bar];
   
    */
    
}

-(void)update:(CFTimeInterval)currentTime {
    /* Called before each frame is rendered */
}

@end

Answer 1

Rassam 所说的 anchor 不准确，默认位置在 (0.5,0.5)。

很明显，这与场景的大小有关。您的场景比屏幕宽。 NSLog 场景的宽度来检验我的假设。