closeBtn.layer.shouldRasterize = YES;
closeBtn.layer.rasterizationScale = [UIScreen mainScreen].scale;
http://www.cocoachina.com/bbs/read.php?tid-1678039.html
closeBtn.layer.shouldRasterize = YES;
closeBtn.layer.rasterizationScale = [UIScreen mainScreen].scale;
http://www.cocoachina.com/bbs/read.php?tid-1678039.html