The Secret Life of a CALayer (Part 4): Setting Shadows (Xcode)

This is a very simple update to the previous project. I want this time to add shadows. We do this by amending the viewDidAppear: method from last time, as shown here:

-(void)viewDidAppear:(BOOL)animated {

    [super viewDidAppear:animated];

    blueLayer = [[CALayer alloc] init];

    positionOne = CGRectMake(100, 100, 100, 100);

    blueLayer.frame = positionOne;

    blueLayer.backgroundColor = [UIColor blueColor].CGColor;

    blueLayer.name = @"One";

    blueLayer.contents = (id) [UIImage imageNamed:@"plane"].CGImage;

    

    [self.view.layer addSublayer:blueLayer];

    

    redLayer = [[CALayer alloc] init];

    positionTwo= CGRectMake(100, 400, 100, 100);

    redLayer.frame = positionTwo;

    redLayer.backgroundColor = [UIColor redColor].CGColor;

    redLayer.name=@"Two";

    

    [self.view.layer addSublayer:redLayer];

    

    yellowLayer = [[CALayer alloc] init];

    positionThree = CGRectMake(400, 100, 100, 100);

    yellowLayer.frame = positionThree;

    yellowLayer.backgroundColor = [UIColor yellowColor].CGColor;

    yellowLayer.name = @"Three";

    

    [self.view.layer addSublayer:yellowLayer];

    

    greenLayer = [[CALayer alloc] init];

    positionFour =  CGRectMake(400, 400, 100, 100);

    greenLayer.frame =positionFour;

    greenLayer.backgroundColor = [UIColor greenColor].CGColor;

    greenLayer.name=@"Four";

    

    [self.view.layer addSublayer:greenLayer];

    

    NSArray *subLevelLayers = [self.view.layer sublayers];

    

    for (CALayer *layerName in subLevelLayers) {

        [layerName setShadowColor:[UIColor blackColor].CGColor];

        [layerName setShadowOpacity:0.25];

        [layerName setShadowRadius:6.0];

        [layerName setShadowOffset:CGSizeMake( 8 , 8)];

    }

    

}

In order to add the shadow we create an NSArray of the sublayers and then cycle through them to set the shadow. For a more detailed and extensive look at CALayer shadows, I highly recommend this post over at designerd.

But if you're staying here, then why don't we go one step further and add a border and curved corners to the layers as well? Easily done, just add the following code to your new "for in" statement.

        layerName.cornerRadius = 5;

        layerName.borderWidth = 2;

        layerName.borderColor =[UIColor grayColor].CGColor;

The Secret Life of a CALayer: Part 1 | Part 2 | Part 3 | Part 4