There you go:
CGRect frame = imageView.bounds;
UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(0, frame.size.height)];
[path addLineToPoint:CGPointMake(0, frame.size.height-60)];
[path addLineToPoint:CGPointMake(frame.size.width/2, frame.size.height-20)];
[path addLineToPoint:CGPointMake(frame.size.width, frame.size.height-60)];
[path addLineToPoint:CGPointMake(frame.size.width, frame.size.height)];
[path closePath];
CAShapeLayer *mask = [CAShapeLayer layer];
mask.path = path.CGPath;
mask.strokeColor = [UIColor clearColor].CGColor;
mask.fillColor = [UIColor colorWithRed:0.1 green:0.1 blue:0.1 alpha:0.5].CGColor;
[imageView.layer addSublayer:mask];
