iOS对项目中所有加阴影的代码进行优化

1、 对项目中所有加阴影的代码进行优化

目前项目中尤其是表格单元格中使用如下加阴影代码严重影响性能(5.2.5航班查询结果页卡顿的原因)

    self.cellBG.layer.shadowColor = [[UIColor colorWithRed:0.8 green:0.8 blue:0.8 alpha:1] CGColor];
    self.cellBG.layer.shadowOffset = CGSizeMake(1, 1);
    self.cellBG.layer.shadowOpacity = 0.5;
self.cellBG.layer.shadowRadius = 2.0;

优化方案如下：
使用setShadowPath，优点：解决性能问题。缺点：需要获取到视图的宽和高，对于自适应的cell

   shadowView.layer.shadowColor = [UIColor redColor].CGColor;
    shadowView.layer.shadowOpacity = 0.5;
    shadowView.layer.shadowRadius = 1.0;
    shadowView.layer.shouldRasterize = YES;
    shadowView.layer.rasterizationScale = [UIScreen mainScreen].scale;
    CGPathRef path = [UIBezierPath bezierPathWithRect:CGRectMake(0.5, 3.5, shadowView.bounds.size.width, shadowView.bounds.size.height)].CGPath;
[shadowView.layer setShadowPath:path];

没用过，不明觉厉。