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