创建没有opengl和cocos2D的粒子.降雪的应用程序

Question

我想在没有openGL或cocs2D的情况下创建像(雪)这样的粒子，我找到了这个名为snowfall的示例代码，在这个代码中有这个:

flakeImage = [UIImage imageNamed:@"flake.png"];
// start a timet that will fire 20 times per second
[NSTimer scheduledTimerWithTimeInterval:(0.5) target:self selector:@selector(onTimer) userInfo:nil repeats:YES];
}

// Timer event is called whenever the timer fires
- (void)onTimer
{

// build a view from our flake image
UIImageView* flakeView = [[UIImageView alloc] initWithImage:flakeImage];
// use the random() function to randomize up our flake attributes
int startX = round(random() % 320);
int endX = round(random() % 320);
double scale = 1 / round(random() % 100) + 1.0;
double speed = 1 / round(random() % 100) + 1.0;
// set the flake start position
flakeView.frame = CGRectMake(startX, -100.0, 5.0 * scale, 5.0 * scale);
flakeView.alpha = 0.25;
// put the flake in our main view
[self.view addSubview:flakeView];
[UIView beginAnimations:nil context:flakeView];
// set up how fast the flake will fall
[UIView setAnimationDuration:5 * speed];
// set the postion where flake will move to
flakeView.frame = CGRectMake(endX, 500.0, 5.0 * scale, 5.0 * scale);
// set a stop callback so we can cleanup the flake when it reaches the
// end of its animation
[UIView setAnimationDidStopSelector:@selector(onAnimationComplete:finished:context:)];
[UIView setAnimationDelegate:self];
[UIView commitAnimations];  }
- (void)onAnimationComplete:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
UIImageView *flakeView = context;
[flakeView removeFromSuperview];
// open the debug log and you will see that all flakes have a retain count 
// of 1 at this point so we know the release below will keep our memory 
// usage in check
NSLog([NSString stringWithFormat:@"[flakeView retainCount] = %d", [flakeView retainCount]]);
[flakeView release];

}

我想知道这段代码是否会损害性能或内存(可能是因为它使用了计时器)?如果这不是一个好主意我听说CAReplicator可以在iphone上使用但是CAReplicatorDemo只能在mac上使用在苹果文档上/抱歉我的英语不好，我是法语:/

Answer 1

当然，这会影响性能。但你不会在模拟器中看到它。UIImageView太重了，每秒不能产生20次。您可以尝试使用CALayer -s池(和CAAnimation)。

Answer 2

你可以在ios5上使用CAEmitterLayer来做粒子效果。我以前用它来处理火焰和烟雾，但它应该可以很好地处理雪。

Answer 3

你可以试试我的KHParticleView，它使用cocos2d粒子并在顶部添加cocos2d视图。查看这里的代码:https://github.com/lephukhanhhuy/KHParticleView