iOS: Create one sideded dropshadow

Question

I have the below menu style layout that mimics facebook. I would like to have a dropshadow on the left side like below however the code I am using with layer shadows makes the application LAGGY. I have not been able to find a good alternative solution. Does anyone have an alternative for creating a dropshadow that does not affect application performance?

[self.navController.view.layer setShadowOffset:CGSizeMake(0, 1)];
[self.navController.view.layer setShadowColor:[[UIColor darkGrayColor] CGColor]];
[self.navController.view.layer setShadowRadius:8.0];
[self.navController.view.layer setShadowOpacity:0.8];

The above code is the code I am currently using that causes application performance issues.

The below image is what I would like to achieve but without having to use the above code.

Answer 1

It should help to specify a shadow path, e.g.,

CGPathRef shadowPath = [UIBezierPath bezierPathWithRect:self.navController.view.layer.bounds].CGPath;
[self.navController.view.layer setShadowPath:shadowPath]

According to the CALayer documentation, "Specifying an explicit path usually improves rendering performance."