CAEmitterLayer - kCAEmitterLayerRectangle render mode?

Question

I want to make particles inside the rectangle.

What is wrong in this code? It is emitted from only the emitter position, not, random position in rectangle.

fireEmitter = [CAEmitterLayer layer];
[self.view.layer fireEmitter];
fireEmitter.emitterPosition = self.view.center;
fireEmitter.emitterSize =CGSizeMake(100, 100);
fireEmitter.renderMode = kCAEmitterLayerRectangle;
fireEmitter.emitterCells = [NSArray arrayWithObjects:fire, nil];

Answer 1

kCAEmitterLayerRectangle is not a valid value for renderMode. Instead you should use one of these values

kCAEmitterLayerUnordered
kCAEmitterLayerOldestFirst
kCAEmitterLayerOldestLast
kCAEmitterLayerBackToFront
kCAEmitterLayerAdditive

The kCAEmitterLayerRectangle value should be set as the emitterShape which defaults to kCAEmitterLayerPoint. That is why you are only emitting from a single point. The valid emitterShapes are:

kCAEmitterLayerPoint
kCAEmitterLayerLine
kCAEmitterLayerRectangle
kCAEmitterLayerCuboid
kCAEmitterLayerCircle
kCAEmitterLayerSphere

Please refer to the documentation for their meaning.