Ios CAEmitterLayer未显示

我只是简单地将一个

UIView

添加到我的

storyboard视图控制器

，然后创建一个

UIView

类来显示粒子效果。我将

ui视图的

类名更改为我创建的自定义类的名称。我在

UIView

类中使用的代码没有显示我期望的粒子效果。代码如下：

- (void)drawRect:(CGRect)rect
{
    // Drawing code

        CGRect viewBounds = rect;

    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

    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;
    burst.scale             = 2.5;
    burst.redSpeed          =-1.5;      // shifting
    burst.blueSpeed         =+1.5;      // shifting
    burst.greenSpeed        =+1.0;      // shifting
    burst.lifetime          = 0.35;

    // and finally, the sparks

    CAEmitterCell* spark = [CAEmitterCell emitterCell];

    spark.birthRate         = 400;
    spark.velocity          = 125;
    spark.emissionRange     = 2* M_PI;  // 360 deg
    spark.yAcceleration     = 75;       // gravity
    spark.lifetime          = 3;

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

    // putting it together
    fireworksEmitter.emitterCells   = [NSArray arrayWithObject:rocket];
    rocket.emitterCells             = [NSArray arrayWithObject:burst];
    burst.emitterCells              = [NSArray arrayWithObject:spark];
    [self.layer addSublayer:fireworksEmitter];

    [self setNeedsDisplay];
}

-（void）drawRect:（CGRect）rect
{
//绘图代码
CGRect viewBounds=rect；
fireworksEmitter.emitterPosition=CGPointMake（viewBounds.size.width/2.0，viewBounds.size.height）；
FireworkSemiter.emitterSize=CGSizeMake（viewBounds.size.width/2.0,0.0）；
fireworksEmitter.emitterMode=KCaemitterLayerRoutline；
fireworksEmitter.emitterShape=kCAEmitterLayerLine；
fireworksEmitter.renderMode=KCaemitterLayerEdit；
fireworksimitter.seed=（arc4random（）%100）+1；
//创造火箭
CAEmitterCell*火箭=[CAEmitterCell发射单元]；
出生率=1.0；
rocket.emissionRange=0.25*M_PI；//角度有一些变化
火箭速度=380；
rocket.velocityRange=100；
火箭加速度=75；
rocket.life=1.02；//我们无法为突发事件设置小于1.0的出生率
rocket.contents=（id）[[UIImage ImageName:@“Dazzing”]CGImage]；
火箭。比例=0.2；
rocket.color=[[UIColor redColor]CGColor]；
rocket.greenRange=1.0；//不同颜色
rocket.redRange=1.0；
rocket.blueRange=1.0；
rocket.spinRange=M_PI；//慢自旋
//无法看到爆裂对象，但会产生火花
//我们在这里更改颜色，因为火花继承了它的值
CAEmitterCell*突发=[CAEmitterCell-emitterCell]；
burst.birthRate=1.0；//在旅行结束时
爆破速度=0；
爆破规模=2.5；
burst.redSpeed=-1.5；//移位
burst.blueSpeed=+1.5；//移位
burst.greenSpeed=+1.0；//移位
爆破寿命=0.35；
//最后，火花
CAEmitterCell*spark=[CAEmitterCell-emitterCell]；
出生率=400；
火花速度=125；
spark.emissionRange=2*M_PI；//360度
spark.yaAcceleration=75；//重力
火花寿命=3；
spark.contents=（id）[[UIImage ImageName:@“DazStarOutline”]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_π；
spark.spinRange=2*M_PI；
//把它放在一起
fireworksimitter.emitterCells=[NSArray arrayWithObject:rocket]；
rocket.emitterCells=[NSArray arrayWithObject:burst]；
burst.emitterCells=[NSArray arrayWithObject:spark]；
[self.layer addSublayer:fireworksimitter]；
[自我设置需要显示]；
}

您的代码看起来不错，因此这里有一些建议

• 您不会显示您正在创建的

  fireworksEmitter

  。如果您没有

  alloc

  和

  init

  将它放在某个地方，您将得到一个没有错误或警告的空白屏幕

• 如果您没有名为“DazRing”和“DazStarOutline”（拼写检查）的（alpha通道）资源，您将得到一个没有错误或警告的空白屏幕

虽然此代码将从内部

drawRect

运行，但这不是一个合适的位置。您没有（直接）进行任何绘图，而是在设置和添加图层。您当然不应该从

drawRect

内部调用

setNeedsDisplay

。如果您将此代码放入（例如）awakeFromNib中（例如）将其从drawRect中删除所有此代码，并将其放入UIView子类init方法中，或者，由于您使用的是storyboard，将其放入awakeFromNib中，则此代码将同样或更好地工作：

- (void)awakeFromNib {
    [super awakeFromNib];

    CGRect viewBounds = rect;

    fireworksEmitter = (CAEmitterLayer*)self.layer;
    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

    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

    CAEmitterCell* burst = [CAEmitterCell emitterCell];
    burst.birthRate         = 1.0;      // at the end of travel
    burst.velocity          = 0;
    burst.scale             = 2.5;
    burst.redSpeed          =-1.5;      // shifting
    burst.blueSpeed         =+1.5;      // shifting
    burst.greenSpeed        =+1.0;      // shifting
    burst.lifetime          = 0.35;

    CAEmitterCell* spark = [CAEmitterCell emitterCell];
    spark.birthRate         = 400;
    spark.velocity          = 125;
    spark.emissionRange     = 2* M_PI;  // 360 deg
    spark.yAcceleration     = 75;       // gravity
    spark.lifetime          = 3;

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

    fireworksEmitter.emitterCells   = [NSArray arrayWithObject:rocket];
    rocket.emitterCells             = [NSArray arrayWithObject:burst];
    burst.emitterCells              = [NSArray arrayWithObject:spark];
}

-（void）从NIB唤醒{
[超级awakeFromNib]；
CGRect viewBounds=rect；
fireworksEmitter=（CAEmitterLayer*）self.layer；
fireworksEmitter.emitterPosition=CGPointMake（viewBounds.size.width/2.0，viewBounds.size.height）；
FireworkSemiter.emitterSize=CGSizeMake（viewBounds.size.width/2.0,0.0）；
fireworksEmitter.emitterMode=KCaemitterLayerRoutline；
fireworksEmitter.emitterShape=kCAEmitterLayerLine；
fireworksEmitter.renderMode=KCaemitterLayerEdit；
fireworksimitter.seed=（arc4random（）%100）+1；
//创造火箭
CAEmitterCell*火箭=[CAEmitterCell发射单元]；
出生率=1.0；
rocket.emissionRange=0.25*M_PI；//角度有一些变化
火箭速度=380；
rocket.velocityRange=100；
火箭加速度=75；
rocket.life=1.02；//我们无法为突发事件设置小于1.0的出生率
rocket.contents=（id）[[UIImage ImageName:@“Dazzing”]CGImage]；
火箭。比例=0.2；
rocket.color=[[UIColor redColor]CGColor]；
rocket.greenRange=1.0；//不同颜色
rocket.redRange=1.0；
rocket.blueRange=1.0；
rocket.spinRange=M_PI；//慢自旋
CAEmitterCell*突发=[CAEmitterCell-emitterCell]；
burst.birthRate=1.0；//在旅行结束时
爆破速度=0；
爆破规模=2.5；
burst.redSpeed=-1.5；//移位
burst.blueSpeed=+1.5；//移位
burst.greenSpeed=+1.0；//移位
爆破寿命=0.35；
CAEmitterCell*spark=[CAEmitterCell-emitterCell]；
出生率=400；
火花速度=125；
spark.emissionRange=2*M_PI；//360度
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