粒子效果-烟花

//分为3种粒子，子弹粒子，爆炸粒子，散开粒子

CAEmitterLayer *fireworksEmitter = [CAEmitterLayer layer];

CGRect viewBounds = self.view.layer.bounds;

fireworksEmitter.emitterPosition = CGPointMake(viewBounds.size.width/2.0, viewBounds.size.height);

fireworksEmitter.emitterSize = CGSizeMake(viewBounds.size.width/2.0, 0.0);

fireworksEmitter.emitterMode = kCAEmitterLayerOutline;

fireworksEmitter.emitterShape = kCAEmitterLayerLine;

fireworksEmitter.renderMode = kCAEmitterLayerAdditive;

fireworksEmitter.seed = (arc4random()%100)+1;

// Create the rocket

CAEmitterCell* rocket = [CAEmitterCell emitterCell];

rocket.birthRate = 1.0;

rocket.emissionRange = 0.25 * M_PI;  // some variation in angle

rocket.velocity = 380;

rocket.velocityRange = 100;

rocket.yAcceleration = 75;

rocket.lifetime = 1.02; // we cannot set the birthrate < 1.0 for the burst

//小圆球图片

rocket.contents = (id) [[UIImage imageNamed:@"DazRing"] CGImage];

rocket.scale = 0.2;

rocket.color = [[UIColor redColor] CGColor];

rocket.greenRange = 1.0; // different colors

rocket.redRange = 1.0;

rocket.blueRange = 1.0;

rocket.spinRange = M_PI; // slow spin

// the burst object cannot be seen, but will spawn the sparks

// we change the color here, since the sparks inherit its value

CAEmitterCell* burst = [CAEmitterCell emitterCell];

burst.birthRate = 1.0; // at the end of travel

burst.velocity = 0;        //速度为0

burst.scale = 2.5;      //大小

burst.redSpeed =-1.5; // shifting

burst.blueSpeed =+1.5; // shifting

burst.greenSpeed =+1.0; // shifting

burst.lifetime = 0.35;    //存在时间

// and finally, the sparks

CAEmitterCell* spark = [CAEmitterCell emitterCell];

spark.birthRate = 400;

spark.velocity = 125;

spark.emissionRange = 2* M_PI; // 360 度

spark.yAcceleration = 75; // gravity

spark.lifetime = 3;

//星星图片

spark.contents = (id) [[UIImage imageNamed:@"爱心"] CGImage];

spark.scaleSpeed =-0.2;

spark.greenSpeed =-0.1;

spark.redSpeed = 0.4;

spark.blueSpeed =-0.1;

spark.alphaSpeed =-0.25;

spark.spin = 2* M_PI;

spark.spinRange = 2* M_PI;

// 3种粒子组合，可以根据顺序，依次烟花弹－烟花弹粒子爆炸－爆炸散开粒子

fireworksEmitter.emitterCells = [NSArray arrayWithObject:rocket];

rocket.emitterCells = [NSArray arrayWithObject:burst];

burst.emitterCells = [NSArray arrayWithObject:spark];

[self.view.layer addSublayer:fireworksEmitter];