iOS开发特殊日子页面变灰处理

//获取RGBA颜色数值
CGFloat r,g,b,a;
[[UIColor lightGrayColor] getRed:&r green:&g blue:&b alpha:&a];
//创建滤镜
id cls = NSClassFromString(@"CAFilter");
id filter = [cls filterWithName:@"colorMonochrome"];
//设置滤镜参数
[filter setValue:@[@(r),@(g),@(b),@(a)] forKey:@"inputColor"];
[filter setValue:@(0) forKey:@"inputBias"];
[filter setValue:@(1) forKey:@"inputAmount"];
//设置给window
[UIApplication sharedApplication].keyWindow.layer.filters = [NSArray arrayWithObject:filter];