触摸速度因场景上的物体数量而异

我正在创建游戏，用户可以用球拍从屏幕顶部击中物体。用户可以连续移动球拍，但如果速度最慢或休息时不应该击中物体，但是如果超过最低速度，用户应击打它们。我已经实现了，但问题是当用户开始触摸与用户触摸连续移动的球拍时，速度变化是他们不以相同速度开始并且当时触摸正在移动也有时候速度非常慢即使运动速度很快。这里是我的一段代码触摸速度因场景上的物体数量而异

-(void)didMoveToView:(SKView *)view { 
self.physicsWorld.contactDelegate = (id)self; 
racketNode = [SKSpriteNode spriteNodeWithImageNamed:@"racket"]; 
racketNode.size = CGSizeMake(50,50); 
racketNode.position = CGPointMake(self.frame.origin.x + self.frame.size.width - 50,50); 
racketNode.name = @"racket"; 
[self addChild:racketNode]; 
} 
-(void) didBeginContact:(SKPhysicsContact *)contact { 
SKSpriteNode *nodeA = (SKSpriteNode *)contact.bodyA.node ; 
SKSpriteNode *nodeB = (SKSpriteNode *) contact.bodyB.node; 
if (([nodeA.name isEqualToString:@"racket"] && [nodeB.name isEqualToString:@"fallingObject"])) { 
    if (racketNode.speed > kMinSpeed) 
     [nodeB removeFromParent]; 
    else { 
     nodeB.physicsBody.contactTestBitMask = 0; 
     [self performSelector:@selector(providingCollsion:) withObject:nodeB afterDelay:0.1]; 
    } 
} 
} 
-(void) providingCollsion:(SKSpriteNode *) node { 

node.physicsBody.contactTestBitMask = racketHit; 
} 

-(void) touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent  *)event { 
for (UITouch *touch in touches) { 
    CGPoint location = [touch locationInNode:self]; 
    start = location; 
    startTime = touch.timestamp; 
    racketNode.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:racketNode.frame.size]; 
    racketNode.physicsBody.categoryBitMask = racket; 
    racketNode.physicsBody.contactTestBitMask = HitIt; 
    racketNode.physicsBody.dynamic = NO; 
    racketNode.physicsBody.affectedByGravity = NO; 
    [racketNode runAction:[SKAction moveTo:location duration:0.01]]; 
} 
} 

- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { 
racketNode.physicsBody = nil; 
racketNode.speed = 0; 
} 

-(void) touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent    *)event { 
UITouch *touch = [touches anyObject]; 
CGPoint location = [touch locationInNode:self]; 
CGFloat dx = location.x - start.x; 
CGFloat dy = location.y - start.y; 
CGFloat magnitude = sqrt(dx*dx+dy*dy); 
// Determine time difference from start of the gesture 
CGFloat dt = touch.timestamp - startTime; 
// Determine gesture speed in points/sec 
CGFloat speed = magnitude/dt; 
racketNode.speed = speed; 
[handNode runAction:[SKAction moveTo:[touch locationInNode:self] duration:0.01]]; 
}

请告诉我哪一部分我的代码是错误的，使同一物体高速只不是速度慢，还对稳定的状态没有碰撞冲突。

来源

2016-08-23 ankit sharma