Create mask layer with image file

gistfile1.m

// Create mask layer
UIImage *maskImage = [UIImage imageNamed:@"posterMask"];
CAShapeLayer* maskLayer = [CAShapeLayer layer];
maskLayer.frame = CGRectMake(0, 0, maskImage.size.width,maskImage.size.height);
maskLayer.contents = (__bridge id)maskImage.CGImage;
self.poster.layer.mask = maskLayer;