如何以越来越快的速度生成精灵

Question

我想知道如何以逐渐增加的速度连续生成精灵。我确实看到了“如何逐渐增加某物的速率？”的问题。但我不确定如何将它应用到我的代码中。此外，如果有比使用游戏计时器更好的定期生成精灵的方法，请告诉我。

我尝试使用循环并增加“scheduledTimerWithTimeInterval”，但它最终导致同时产生大量精灵。

-(void)getBalls {


//[userScore.node removeFromParent];

SKSpriteNode *ball = [SKSpriteNode spriteNodeWithImageNamed:@"ball"];

int x = arc4random() %320;

CGPoint myPoint = CGPointMake(x, 480);
ball.position = myPoint;

ball.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:ball.frame.size.width/2];

ball.physicsBody.categoryBitMask = ballCategory;

ball.physicsBody.contactTestBitMask = paddleCategory;

ball.physicsBody.collisionBitMask = ballCategory;

[self addChild:ball];

SKLabelNode *userScore = [SKLabelNode labelNodeWithFontNamed:@"Impact"];
userScore.fontColor = [SKColor blackColor];
userScore.text = [NSString stringWithFormat:@"SCORE: %i", score];
userScore.fontSize = 18;
userScore.position = CGPointMake(CGRectGetMidX(self.frame) + 110, CGRectGetHeight(self.frame)            
- 30);
[self addChild:userScore];
[userScore runAction:[SKAction fadeAlphaTo:1.0 duration:1.5] completion:^{
    [userScore removeFromParent];
}];




}

-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
self.backgroundColor = [SKColor  whiteColor];


self.physicsWorld.gravity = CGVectorMake(0, -9.8);
self.physicsWorld.contactDelegate = self;

gameTimer = [NSTimer scheduledTimerWithTimeInterval:1.5 target:self      
selector:@selector(getBalls) userInfo:nil repeats:YES];

[self addPlayer:size];


}

感谢您的帮助。

Answer 1

使用非重复的 NSTimer。此外，在计时器调用的方法 (getBalls) 中，调用计时器并降低间隔率（线性、指数，随心所欲）。

---

float decTime;
decTime = 1.5f;

---

-(id)initWithSize:(CGSize)size {

    if (self = [super initWithSize:size]) {
    self.backgroundColor = [SKColor  whiteColor];

    self.physicsWorld.gravity = CGVectorMake(0, -9.8);
    self.physicsWorld.contactDelegate = self;

    gameTimer = [NSTimer scheduledTimerWithTimeInterval:decTime target:self      
    selector:@selector(getBalls) userInfo:nil repeats:NO];

    [self addPlayer:size];

}

-(void)getBalls {


    //[userScore.node removeFromParent];

    SKSpriteNode *ball = [SKSpriteNode spriteNodeWithImageNamed:@"ball"];

    int x = arc4random() %320;

    CGPoint myPoint = CGPointMake(x, 480);
    ball.position = myPoint;

    ball.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:ball.frame.size.width/2];

    ball.physicsBody.categoryBitMask = ballCategory;

    ball.physicsBody.contactTestBitMask = paddleCategory;

    ball.physicsBody.collisionBitMask = ballCategory;

    [self addChild:ball];

    ....

    if (decTime > .05f) {

        //linear increase
        decTime -= .01f;

        gameTimer = [NSTimer scheduledTimerWithTimeInterval:decTime target:self      
        selector:@selector(getBalls) userInfo:nil repeats:NO];

    }
}