UIViewに影

UIViewを重ね、奥行き感を出すために手前のUIViewに影をつける場合

// uiviewはUIViewのインスタンス
CALayer *caLayer = uiview.layer;
caLayer.rasterizationScale = [[UIScreen mainScreen] scale];
caLayer.shadowRadius = 3.0f;
caLayer.shadowOpacity = 1.5f;
caLayer.shadowOffset = CGSizeMake(0.0f, 1.0f);
caLayer.shouldRasterize = YES;