Crear sombra en una view
CALayer *layer = [self.vDialog layer];
[layer setMasksToBounds:NO ];
[layer setShadowColor:[[UIColor lightGrayColor] CGColor]];
[layer setShadowOpacity:0.6 ];
[layer setShadowRadius:6.0 ];
[layer setShadowOffset:CGSizeMake( 0 , 0 )];
[layer setShouldRasterize:NO];
[layer setCornerRadius:5.0];
[layer setBorderColor:[UIColor lightGrayColor].CGColor];
[layer setBorderWidth:0.1];
CGRect frame = CGRectMake(-5, -5, self.frame.size.width-70, self.dialogHeight.constant+10);
[layer setShadowPath:[UIBezierPath bezierPathWithRect:frame].CGPath];