CoreAnimation之CAEmitterLayer(粒子破

在iOS 5中，苹果引入了一个新的CALayer子类叫做CAEmitterLayer。CAEmitterLayer是一个高性能的粒子引擎，被用来创建实时例子动画如：烟雾，火，雨等等这些效果。
CAEmitterLayer看上去像是许多CAEmitterCell的容器，这些CAEmitierCell定义了一个例子效果。你将会为不同的例子效果定义一个或多个CAEmitterCell作为模版，同时CAEmitterLayer负责基于这些模版实例化一个粒子流。一个CAEmitterCell类似于一个CALayer：它有一个contents属性可以定义为一个CGImage，另外还有一些可设置属性控制着表现和行为。我们不会对这些属性逐一进行详细的描述，你们可以在CAEmitterCell类的头文件中找到。

** CAEmitterLayer类提供了一个粒子发射器系统为核心的动画。这些粒子是由CAEmitterCell组成的实例，它相当于一个管理者，来管理 CAEmitterCell的发射的一些细节，比如发射的位置，发射形状等等**

CAEmitterCell属性

@interface ViewController () 
@property (nonatomic, weak) IBOutlet UIView *containerView; 
@end 
@implementation ViewController 

- (void)viewDidLoad {
 [super viewDidLoad]; 
//create particle emitter layer 
CAEmitterLayer *emitter = [CAEmitterLayer layer];
 emitter.frame = self.containerView.bounds; [self.containerView.layer addSublayer:emitter]; 
//configure emitter emitter.renderMode = kCAEmitterLayerAdditive; 
emitter.emitterPosition = CGPointMake(emitter.frame.size.width / 2.0, emitter.frame.size.height / 2.0); 
//create a particle template 
CAEmitterCell *cell = [[CAEmitterCell alloc] init]; 
cell.contents = (__bridge id)[UIImage imageNamed:@"Spark.png"].CGImage; cell.birthRate = 150; 
cell.lifetime = 5.0;
 cell.color = [UIColor colorWithRed:1 green:0.5 blue:0.1 alpha:1.0].CGColor; 
cell.alphaSpeed = -0.4; 
cell.velocity = 50;
 cell.velocityRange = 50; 
cell.emissionRange = M_PI * 2.0; //add particle template to emitter emitter.emitterCells = @[cell]; 
} 
@end

点赞的破碎动画

    self.view.backgroundColor =[UIColor whiteColor];
    
    self.container =[[UIView alloc]initWithFrame:CGRectMake(0, 0, 30, 30)];
    self.container.layer.contents = (__bridge id)[UIImage imageNamed:@"点赞2"].CGImage;
    self.container.center = self.view.center;
    [self.view addSubview:self.container];
    CAEmitterCell *emitterCell = [CAEmitterCell emitterCell];
    emitterCell.name           = @"emitter";
    emitterCell.alphaRange     = 0.10;
    emitterCell.alphaSpeed     = -1.0;
    emitterCell.lifetime       = 0.6;
    emitterCell.lifetimeRange  = 0.3;
    emitterCell.birthRate      = 0;
    emitterCell.velocity       = 40.00;
    emitterCell.velocityRange  = 10.00;
    emitterCell.scale          = 0.03;
    emitterCell.scaleRange     = 0.02;
    emitterCell.contents       = (id)[UIImage imageNamed:@"Emitter"].CGImage;
    
     self.emitterLayer               = [CAEmitterLayer layer];
     self.emitterLayer.name          = @"emitterLayer";
     self.emitterLayer.emitterShape  = kCAEmitterLayerCircle;
     self.emitterLayer.emitterMode   = kCAEmitterLayerOutline;
     self.emitterLayer.emitterSize   = CGSizeMake(20, 20);
     self.emitterLayer.emitterCells  = @[emitterCell];
     self.emitterLayer.renderMode    = kCAEmitterLayerAdditive;
     self.emitterLayer.masksToBounds = NO;
     self.emitterLayer.position      = CGPointMake(self.container.frame.size.width/2.0,self.container.frame.size.height/2.0);

    [self.container.layer addSublayer:self.emitterLayer];