iOS CAEmitterCell 烟花效果

Question

我想创造一个像烟花一样的效果。我知道我可以使用 CAEmitterCell。我尝试下载几个示例，但我仍在 iOS 5.0 中使用此功能

有人知道如何使用CAEmitterCell制作烟花效果的好教程吗？

我需要创建如下内容：

所有粒子都从中心（红色圆圈）向绿色圆圈方向移动。红圈这是初始点，会有一些 CGPoint 值。

Answer 1

我找到了这个解决方案：

这是 DWFParticleView.h 文件的外观

#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

这就是 DWFParticleView.m 的样子

#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

这是一个点击屏幕的方法，例如显示我们的效果

- (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];
}

我在这里找到的材料：ray