根据业务不一样，大致产品会有两种需求：
需求1：全部设置为黑白色
需求2：某个界面设置为黑白色
大致的实现方案：
方案一：
服务端下发所有黑(灰)图片，字体颜色支持动态下发
这个，如果是只有某个界面还好，如果是全量替换图片，工作量太大
方案二：
里面大致涉及到：image、UILabel的color、UIButton的Color、webView、Video等等
对于image，一般都是使用UIImageView去显示，因此，利用runtime里面的方法交换，让setImage:方法走自己的。
然后在私有方法里面实现对图片添加滤镜
+ (void)load {
Method customMethod = class_getInstanceMethod([self class], @selector(setImage:));
Method originMethod = class_getInstanceMethod([self class], @selector(gl_setImage:));
method_exchangeImplementations(customMethod, originMethod);//方法交换
}
- (void)gl_setImage:(UIImage *)image {
//是否黑白化,1表示开启
BOOL isOpenWhiteBlackModel = [[NSUserDefaults standardUserDefaults] boolForKey:@"kIsShowBlackWhiteModel"];
if (isOpenWhiteBlackModel == 1) {
[self gl_setImage:[self gl_grayImage:image]];
} else {
[self gl_setImage:image];
}
}
- (UIImage *)gl_grayImage:(UIImage *)image {
//UIKBSplitImageView是为了键盘
if (image == nil || [self.superview isKindOfClass:NSClassFromString(@"UIKBSplitImageView")]) {
return image;
}
//滤镜处理
//CIPhotoEffectNoir黑白
//CIPhotoEffectMono单色
NSString *filterName = @"CIPhotoEffectMono";
CIFilter *filter = [CIFilter filterWithName:filterName];
CIImage *inputImage = [[CIImage alloc] initWithImage:image];
[filter setValue:inputImage forKey:kCIInputImageKey];
CGImageRef cgImage = [self.filterContext createCGImage:filter.outputImage fromRect:[inputImage extent]];
UIImage *resultImg = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
return resultImg;
}
- (CIContext *)filterContext {
CIContext *con = objc_getAssociatedObject(self, @selector(filterContext));
if (!con) {
con = [[CIContext alloc] initWithOptions:nil];
self.filterContext = con;
}
return con;
}
- (void)setFilterContext:(CIContext *)filterContext {
objc_setAssociatedObject(self, @selector(filterContext), filterContext, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
H5变灰—分类
WKWebView+blackWhiteModel.m文件：
#import "WKWebView+blackWhiteModel.h"
#import <objc/runtime.h>
@implementation WKWebView (blackWhiteModel)
+ (void)load {
Method customMethod = class_getInstanceMethod([self class], @selector(gl_initWithFrame:configuration:));
Method originMethod = class_getInstanceMethod([self class], @selector(initWithFrame:configuration:));
method_exchangeImplementations(customMethod, originMethod);//方法交换
}
- (instancetype)gl_initWithFrame:(CGRect)frame configuration:(WKWebViewConfiguration *)configuration
{
BOOL isOpenWhiteBlackModel = [[NSUserDefaults standardUserDefaults] boolForKey:@"kIsShowBlackWhiteModel"];
if (isOpenWhiteBlackModel) {
// js脚本
NSString *jScript = @"var filter = '-webkit-filter:grayscale(100%);-moz-filter:grayscale(100%); -ms-filter:grayscale(100%); -o-filter:grayscale(100%) filter:grayscale(100%);';document.getElementsByTagName('html')[0].style.filter = 'grayscale(100%)';";
// 注入
WKUserScript *wkUScript = [[WKUserScript alloc] initWithSource:jScript injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
WKUserContentController *wkUController = [[WKUserContentController alloc] init];
[wkUController addUserScript:wkUScript];
// 配置对象
WKWebViewConfiguration *wkWebConfig = [[WKWebViewConfiguration alloc] init];
wkWebConfig.userContentController = wkUController;
configuration = wkWebConfig;
WKWebView *webView = [self gl_initWithFrame:frame configuration:configuration];
return webView;
}
return [self gl_initWithFrame:frame configuration:configuration];
}
@end
上述方案有个问题，因为是替换的init方法，会导致在开关为0之前的webView都是彩色、开关为1之后的webView都是灰色
因此，务必确认，请求是否开关的结果在创建webView之前，还是之后
H5变灰—单个
可以针对单个的H5做变灰处理
跟上面的js代码都一样：
BOOL isOpenWhiteBlackModel = [[NSUserDefaults standardUserDefaults] boolForKey:@"kIsShowBlackWhiteModel"];
WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
WKUserContentController *userController = [[WKUserContentController alloc] init];
configuration.userContentController = userController;
if (isOpenWhiteBlackModel) {
//悼念日模式 替换wkView整体主题色
[userController addUserScript:[self getJsStr]];
}
-(WKUserScript *)getJsStr{
NSString *jScript = @"var filter = '-webkit-filter:grayscale(100%);-moz-filter:grayscale(100%); -ms-filter:grayscale(100%); -o-filter:grayscale(100%) filter:grayscale(100%);';document.getElementsByTagName('html')[0].style.filter = 'grayscale(100%)';";
// 注入
WKUserScript *wkUScript = [[WKUserScript alloc] initWithSource:jScript injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
return wkUScript;
}
其他UILabel、UIButton等的分类可参考：
https://github.com/GeLeis/App_NoirDemo
方案三：
图片处理与方案二类似
而Label、View等的color不再一个一个做分类处理，直接修改Color的分类
+ (void)load {
//关键方法交换
Method customMethod = class_getClassMethod([self class], @selector(gl_colorWithRed:green:blue:alpha:));
Method originMethod = class_getClassMethod([self class], @selector(colorWithRed:green:blue:alpha:));
method_exchangeImplementations(customMethod, originMethod);//方法交换
}
+ (UIColor *)gl_colorWithRed:(CGFloat)red green:(CGFloat)green blue:(CGFloat)blue alpha:(CGFloat)alpha {
//如果是单色模式(黑白模式),则平均r、g、b值
//是否黑白化,1表示开启
BOOL isOpenWhiteBlackModel = [[NSUserDefaults standardUserDefaults] boolForKey:@"kIsShowBlackWhiteModel"];
if (isOpenWhiteBlackModel) {
//r,g,b权重调整,防止出现,1 0 0 、0 1 0,0 0 1同样的结果
//0.2126，0.7152，0.0722 这三个是根据人眼对r,g,b三个颜色面感的强弱算出来的
CGFloat brightness = (red * 0.2126 + 0.7152 * green + 0.0722 * blue);
return [self gl_colorWithRed:brightness green:brightness blue:brightness alpha:alpha];
}
return [self gl_colorWithRed:red green:green blue:blue alpha:alpha];
}
方案四：
不再通过runtime的方法，而是直接为view添加灰色滤镜
//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
self.window.layer.filters = [NSArray arrayWithObject:filter];
r, g, b, a的值都可以直接修改，而非必须是[UIColor lightGrayColor]
如果只是某个控制器A，则设置A.view.layer.filters = [NSArray arrayWithObject:filter];即可
当然，还有其他filter可以供使用
id cls = NSClassFromString(@"CAFilter");
id filter = [cls filterWithName:@"colorSaturate"];
[filter setValue:@(0) forKey:@"inputAmount"];
//设置给window
self.window.layer.filters = [NSArray arrayWithObject:filter];
CAFilter为苹果私有方法，有被拒可能，因此，没有用这个方法
最终做法
添加一个view，里面不接收点击事件
@interface ZRLandlordHPGrayView : UIView
@end
@implementation ZRLandlordHPGrayView
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
return nil;
}
@end
然后，在需要显示黑白模式的界面，添加如下方法：
- (void)showGrayViewWithSuperView:(UIView *)superView
{
//该方法是用来存储是否为黑白模式
BOOL isOpenWhiteBlackModel = [[NSUserDefaults standardUserDefaults] boolForKey:@"kIsShowBlackWhiteModel"];
if (isOpenWhiteBlackModel) {
if (@available(iOS 12.0, *)) {//只支持12及以上
ZRLandlordHPGrayView *overlay = [[ZRLandlordHPGrayView alloc] initWithFrame:superView.bounds];
overlay.userInteractionEnabled = NO;
overlay.translatesAutoresizingMaskIntoConstraints = false;
overlay.backgroundColor = [UIColor grayColor];
overlay.layer.compositingFilter = @"saturationBlendMode";
[superView addSubview:overlay];
[superView bringSubviewToFront:overlay];
}
}
}
该做法只支持12及12以上
看了下我们的app，12以下的基本上凤毛麟角，所以最终选择了这种方法
其他参考文章：
iOS界面置灰方案讨论
iOS 悼念日模式
在iOS使用黑魔法实现一键全局图片变灰白的一种方案
iOS APP界面黑白化处理（灰度处理）（为悼念日准备)