CAEmitterLayer not visible in my View Controller - objective-c

Question

I'm trying to add a simple particle effect overlay to one of my UIViewController instances. I've followed a couple of tutorials I found, but neither of them deal with view controllers and their storyboards are just a view out on its own with no controller, which is confusing.
Here's my code, I'm just trying to figure out why I can't see the particle effects. What am I missing? The view itself is definitely there and added (if I change its color or something I can see it), it's just empty, and isn't showing any particle effects. The image file referenced is definitely in the project and target, so what else have I done wrong here? Do I need to add the CAEmitterLayer to rainView somehow? The tutorials didn't offer any help on this part!
RainfallOverlay.h
#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>
#interface RainfallOverlay : UIView {
CAEmitterLayer *rainEmitter;
}
#end
RainfallOverlay.m
#import "RainfallOverlay.h"
#implementation RainfallOverlay
- (void) awakeFromNib
{
rainEmitter = (CAEmitterLayer *) self.layer;
rainEmitter.emitterPosition = CGPointMake(160, 100);
rainEmitter.emitterSize = CGSizeMake(10, 10);
rainEmitter.renderMode = kCAEmitterLayerAdditive;
CAEmitterCell *rain = [CAEmitterCell emitterCell];
rain.birthRate = 200;
rain.lifetime = 2.0;
rain.lifetimeRange = 1.5;
rain.color = [[UIColor colorWithRed: 0.2 green: 0.4 blue: 0.8 alpha: 0.1] CGColor];
rain.contents = (id) [[UIImage imageNamed: #"Particles_rain.png"] CGImage];
rain.name = #"rain";
rain.velocity = 150;
rain.velocityRange = 100;
rain.emissionRange = M_PI_2;
rain.emissionLongitude = 0.025 * 180 / M_PI;
rain.scaleSpeed = 0;
rain.spin = 0.5;
rainEmitter.emitterCells = [NSArray arrayWithObject: rain];
}
#end
ViewController.m viewDidLoad
RainfallOverlay *rainView = [[RainfallOverlay alloc] initWithFrame: CGRectMake(0, 0, 320, 250)];
[rainView setUserInteractionEnabled: NO];
[self.view bringSubviewToFront: rainView];
[self.view addSubview: rainView];

Answer 1

There are 2 problems:
awakeFromNib would only be called if the view is loaded from a nib file. In your case, you have to implement initWithFrame.
You have to override layerClass to that self.layer returns a CAEmitterLayer. Just casting the layer to CAEmitterLayer does not work.
So your RainfallOverlay implementation should look like this:
+ (Class)layerClass
{
return [CAEmitterLayer class];
}
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
rainEmitter = (CAEmitterLayer *) self.layer;
// ... remaining setup
}
return self;
}