iOS – Just a quick way to create a shadow on any view

Sometimes you would want a shadow on a view.
Easiest and quickest way is to just add it on the view’s layer:
[sourcecode language=”c”]
-(void)loadView {
CGRect frame = [[UIScreen mainScreen] applicationFrame];
self.view = [[UIView alloc] initWithFrame:frame];
self.view.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
self.view.backgroundColor = [UIColor blackColor];
UIView *glowView = [[UIView alloc] initWithFrame:CGRectMake(frame.size.width /2 -10, frame.size.height /2 -30, 20, 60)];
glowView.autoresizingMask = UIViewAutoresizingFlexibleBottomMargin |
UIViewAutoresizingFlexibleTopMargin |
UIViewAutoresizingFlexibleLeftMargin |
UIViewAutoresizingFlexibleRightMargin;
glowView.backgroundColor = [UIColor whiteColor];
[self.view addSubview:glowView];
//Setup the shadow on the view’s CALayer.
CALayer *viewLayer = glowView.layer;
viewLayer.shadowOffset = CGSizeMake(0, 0);
viewLayer.shadowColor = [[UIColor yellowColor] CGColor];
viewLayer.shadowPath = [UIBezierPath bezierPathWithRect:glowView.bounds].CGPath;
viewLayer.shadowRadius = 10.0f;
viewLayer.shadowOpacity = 1.0f;
//Let’s animate it while we’re at it.
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"shadowOpacity"];
animation.duration = 0.5f;
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
animation.fromValue = [NSNumber numberWithFloat:1.0];
animation.toValue = [NSNumber numberWithFloat:0.0];
animation.autoreverses = YES;
animation.repeatCount = HUGE_VALF;
[viewLayer addAnimation:animation forKey:@"shadowOpacity"];
}
[/sourcecode]
I must admit, this is kind of basic stuff. But it seems a lot of people actually forget about the fact that all UIView subclasses are based on Core Animation CALayers.
See the source code https://github.com/xebia/ios-DemoForBlog and try the example, the interesting bits about this example are all contained within the fourth tab of the application, it’s the XSDFourthViewController in the code.