能产生粒子效果的CAEmitterLayer

下雪效果:

//
//  RootViewController.m
//  Cell
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "RootViewController.h"

@interface RootViewController ()

@end

@implementation RootViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.view.backgroundColor  = [UIColor blackColor];

    // 创建粒子Layer
    CAEmitterLayer *snowEmitter = [CAEmitterLayer layer];

    // 粒子发射位置
    snowEmitter.emitterPosition = CGPointMake(120,20);

    // 发射源的尺寸大小
    snowEmitter.emitterSize = self.view.bounds.size;

    // 发射模式
    snowEmitter.emitterMode = kCAEmitterLayerSurface;

    // 发射源的形状
    snowEmitter.emitterShape = kCAEmitterLayerLine;

    // 创建雪花类型的粒子
    CAEmitterCell *snowflake = [CAEmitterCell emitterCell];

    // 粒子的名字
    snowflake.name = @"snow";

    // 粒子参数的速度乘数因子
    snowflake.birthRate = 1.0;
    snowflake.lifetime = 120.0;

    // 粒子速度
    snowflake.velocity =10.0;

    // 粒子的速度范围
    snowflake.velocityRange = 10;

    // 粒子y方向的加速度分量
    snowflake.yAcceleration = 2;

    // 周围发射角度
    snowflake.emissionRange = 0.5 * M_PI;

    // 子旋转角度范围
    snowflake.spinRange = 0.25 * M_PI;
    snowflake.contents = (id)[[UIImage imageNamed:@"snow"] CGImage];

    // 设置雪花形状的粒子的颜色
    snowflake.color = [[UIColor whiteColor] CGColor];

    snowflake.scaleRange = 0.6f;
    snowflake.scale = 0.7f;

    snowEmitter.shadowOpacity = 1.0;
    snowEmitter.shadowRadius = 0.0;
    snowEmitter.shadowOffset = CGSizeMake(0.0, 0.0);

    // 粒子边缘的颜色
    snowEmitter.shadowColor = [[UIColor whiteColor] CGColor];

    // 添加粒子
    snowEmitter.emitterCells = @[snowflake];

    // 将粒子Layer添加进图层中
    [self.view.layer addSublayer:snowEmitter];
}

@end

烟花效果:

//
//  RootViewController.m
//  Cell
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "RootViewController.h"

@interface RootViewController ()

@end

@implementation RootViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.view.backgroundColor  = [UIColor blackColor];

    // Cells spawn in the bottom, moving up
    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

    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:@"snow"] 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.view.layer addSublayer:fireworksEmitter];
}

@end

/* The birth rate of each cell is multiplied by this number to give the
 * actual number of particles created every second. Default value is one.
 * Animatable. */

@property float birthRate;

/* The cell lifetime range is multiplied by this value when particles are
 * created. Defaults to one. Animatable. */

@property float lifetime;

/* The center of the emission shape. Defaults to (0, 0, 0). Animatable. */

@property CGPoint emitterPosition;
@property CGFloat emitterZPosition;

/* The size of the emission shape. Defaults to (0, 0, 0). Animatable.
 * Depending on the `emitterShape‘ property some of the values may be
 * ignored. */

@property CGSize emitterSize;
@property CGFloat emitterDepth;

/* Multiplies the cell-defined particle velocity. Defaults to one.
 * Animatable. */

@property float velocity;

/* Multiplies the cell-defined particle scale. Defaults to one. Animatable. */

@property float scale;

/* Multiplies the cell-defined particle spin. Defaults to one. Animatable. */

@property float spin;

你需要知道的非常重要的细节:

CAEmitterCell的动画属性挺多的,但有点奇葩的是,必须是通过KVC设置值才行的通,而且,动画结束时的值也必须通过KVC设置才有效......

//
//  RootViewController.m
//  Cell
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "RootViewController.h"
#import "YXGCD.h"

@interface RootViewController ()

@end

@implementation RootViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.view.backgroundColor  = [UIColor blackColor];

    // 创建粒子Layer
    CAEmitterLayer *snowEmitter = [CAEmitterLayer layer];

    // 粒子发射位置
    snowEmitter.emitterPosition = CGPointMake(120,20);

    // 发射源的尺寸大小
    snowEmitter.emitterSize = self.view.bounds.size;

    // 发射模式
    snowEmitter.emitterMode = kCAEmitterLayerSurface;

    // 发射源的形状
    snowEmitter.emitterShape = kCAEmitterLayerLine;

    // 创建雪花类型的粒子
    CAEmitterCell *snowflake = [CAEmitterCell emitterCell];

    // 粒子参数的速度乘数因子
    snowflake.birthRate = 20.0;
    snowflake.lifetime = 120.0;

    // 粒子速度
    snowflake.velocity =10.0;

    // 粒子的速度范围
    snowflake.velocityRange = 10;

    // 粒子y方向的加速度分量
    snowflake.yAcceleration = 200;

    // 周围发射角度
    snowflake.emissionRange = 0.5 * M_PI;

    // 子旋转角度范围
    snowflake.spinRange = 0.25 * M_PI;
    snowflake.contents = (id)[[UIImage imageNamed:@"snow"] CGImage];

    // 设置雪花形状的粒子的颜色
    snowflake.color = [[UIColor whiteColor] CGColor];

    snowEmitter.shadowOpacity = 1.0;
    snowEmitter.shadowRadius = 0.0;
    snowEmitter.shadowOffset = CGSizeMake(0.0, 0.0);

    // 粒子边缘的颜色
    snowEmitter.shadowColor = [[UIColor whiteColor] CGColor];

    // 粒子的名字
    snowflake.name = @"snow";

    // 添加粒子
    snowEmitter.emitterCells = @[snowflake];

    // 将粒子Layer添加进图层中
    [self.view.layer addSublayer:snowEmitter];

    // 7秒后执行
    [[GCDQueue mainQueue] execute:^{

        // 设置基本动画
        CABasicAnimation *ani =             [CABasicAnimation animationWithKeyPath:@"emitterCells.snow.birthRate"];
        ani.fromValue = @(20.0);
        ani.toValue   = @(0.0);
        ani.duration  = 12.f;

        // 设置结束时的值
        [snowEmitter setValue:[NSNumber numberWithFloat:0]
                   forKeyPath:@"emitterCells.snow.birthRate"];

        // 添加动画
        [snowEmitter addAnimation:ani forKey:nil];

    } afterDelay:NSEC_PER_SEC * 7];
}

@end

能产生粒子效果的CAEmitterLayer