Question

I’m wanna create an effect like firework. I know that I can use for it CAEmitterCell. I tried to download few examples, but I still in progress with this feature in iOS 5.0

Anybody know good tutorial how to create firework effect using CAEmitterCell?

I need to create something like below:

All particles are going from the center (red circle) in direction to green circles. Red circle this is initial point that will have some CGPoint value.

Answer 1

I have found this solution:

it’s how DWFParticleView.h file looks

#import <UIKit/UIKit.h>

@interface DWFParticleView : UIView

@property (nonatomic) CGFloat time;

-(void)configurateEmmiter;
-(void)setEmitterPositionFromTouch: (UITouch*)t;
-(void)setIsEmitting:(BOOL)isEmitting andPoint:(CGPoint)point;

@end

this is how looks DWFParticleView.m

#import "DWFParticleView.h"
#import <QuartzCore/QuartzCore.h>

@implementation DWFParticleView
{
    CAEmitterLayer* fireEmitter; //1
}

-(void)configurateEmmiter
{
    //set ref to the layer
    fireEmitter = (CAEmitterLayer*)self.layer; //2

    //configure the emitter layer
    fireEmitter.emitterPosition = CGPointMake(50, 50);
    fireEmitter.emitterSize = CGSizeMake(5, 5);

    CAEmitterCell* fire = [CAEmitterCell emitterCell];
    fire.birthRate = 0;
    fire.lifetime = 2.0;
    fire.lifetimeRange = 0.5;
    //fire.color = [[UIColor colorWithRed:0.8 green:0.4 blue:0.2 alpha:0.6] CGColor];
    fire.contents = (id)[[UIImage imageNamed:@"star_icon.png"] CGImage];
    [fire setName:@"fire"];


    fire.velocity = 80;
    fire.velocityRange = 20;
    fire.emissionRange = M_PI * 2.0f;

    fire.scaleSpeed = 0.1;
    fire.spin = 0.5;

    //add the cell to the layer and we're done
    fireEmitter.emitterCells = [NSArray arrayWithObject:fire];

    fireEmitter.renderMode = kCAEmitterLayerAdditive;

}

+ (Class) layerClass {
    return [CAEmitterLayer class];
}

-(void)setEmitterPositionFromTouch: (UITouch*)t
{
    //change the emitter's position
    fireEmitter.emitterPosition = [t locationInView:self];
}

-(void)setIsEmitting:(BOOL)isEmitting andPoint:(CGPoint)point
{

    fireEmitter.emitterPosition = point;

    //turn on/off the emitting of particles
    [fireEmitter setValue:[NSNumber numberWithInt:isEmitting?50:0]
               forKeyPath:@"emitterCells.fire.birthRate"];


    [self performSelector:@selector(decayStep) withObject:nil afterDelay:self.time];
}

- (void)decayStep {
    [fireEmitter setValue:[NSNumber numberWithInt:0]
               forKeyPath:@"emitterCells.fire.birthRate"];
}

@end

this is method one tap on screen for example that shows our effect

- (void)tap {
    DWFParticleView *fireView = [[DWFParticleView alloc] init];
    fireView.time = 0.3;
    [fireView setUserInteractionEnabled:NO];
    [fireView configurateEmmiter];
    [fireView setFrame:CGRectMake(0, 0, 0, 0)];
    [fireView setBackgroundColor:[UIColor redColor]];
    [self.view addSubview:fireView];
}

the material I have found here: ray