ios - Draw shadow only from 3 sides of UIView

Question

I've successfully implemented drawing a shadow around my UIView like this:

block1.layer.masksToBounds = NO;
block1.layer.shadowOffset = CGSizeMake(0, 0);
block1.layer.shadowRadius = 1;
block1.layer.shadowOpacity = 0.7;

What now happens is I have a rectangular UIView and i would like to draw the shadow around it three sides, leaving the bottom side of it without the shadow.

I know that I have to specify the block1.layer.shadowPath by creating a new UIBezierPath but I'm not sure how to do it.

Obviously, setting layer.shadowOffset won't do the trick for me.

Thanks in advance!

Answer 1

I know you say setting layer.shadowOffset won't work for you, but you are allowed to put in negative values so setting it layer.shadowOffset = CGSizeMake(0.0, -2.0) would come close to the effect you're looking for but of course I expect you want it to be even on the three sides.

So here we go with layer.shadowPath!

UIView *block1 = [[UIView alloc] initWithFrame:CGRectMake(32.0, 32.0, 128.0, 128.0)];
[block1 setBackgroundColor:[UIColor orangeColor]];
[self.view addSubview:block1];

block1.layer.masksToBounds = NO;
block1.layer.shadowOffset = CGSizeMake(0, 0);
block1.layer.shadowRadius = 1;
block1.layer.shadowOpacity = 0.7;

UIBezierPath *path = [UIBezierPath bezierPath];

// Start at the Top Left Corner
[path moveToPoint:CGPointMake(0.0, 0.0)];

// Move to the Top Right Corner
[path addLineToPoint:CGPointMake(CGRectGetWidth(block1.frame), 0.0)];

// Move to the Bottom Right Corner
[path addLineToPoint:CGPointMake(CGRectGetWidth(block1.frame), CGRectGetHeight(block1.frame))];

// This is the extra point in the middle :) Its the secret sauce.
[path addLineToPoint:CGPointMake(CGRectGetWidth(block1.frame) / 2.0, CGRectGetHeight(block1.frame) / 2.0)];

// Move to the Bottom Left Corner
[path addLineToPoint:CGPointMake(0.0, CGRectGetHeight(block1.frame))];

// Move to the Close the Path
[path closePath];

block1.layer.shadowPath = path.CGPath;

And to give you an idea of whats going on, here is the actual shadow path you just drew :)

Its possible to just shift that extra middle point before or after the other lines to choose which side will be omitted.