Shadows

You can use 5 properties on each layer to configure your shadows:

• shadowOffset - this property moves your shadow left/right or up/down

self.layer.shadowOffset = CGSizeMake(-1, -1); // 1px left and up

self.layer.shadowOffset = CGSizeMake(1, 1); // 1px down and right

• shadowColor - this sets the color of your shadow

self.layer.shadowColor = [UIColor blackColor].CGColor;

• shadowOpacity - this is the opacity of the shadow, from 0 to 1

self.layer.shadowOpacity = 0.2;

• shadowRadius - this is the blur radius (equivalent of the blur property in Sketch or Photoshop)

self.layer.shadowRadius = 6;

• shadowPath - this is an important property for performance, when unset iOS bases the shadow on the alpha channel of the view, which can be performance intensive with a complex PNG with alpha. This property lets you force a shape for your shadow and be more performant because of it.

Objective-C

self.layer.shadowPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0,0,100,100)]; //this does a circular shadow

Swift 3

self.layer.shadowPath = UIBezierPath(ovalIn: CGRect(x: 0, y: 0, width: 100, height: 100)).cgPath