iOS整个APP实现灰色主题的示例代码

//image类别
- (UIImage *)getGrayImage {
    
  const int RED =1;
  const int GREEN =2;
  const int BLUE =3;
    
  UIImage *image = self;
    
  // Create image rectangle with current image width/height
  CGRect imageRect = CGRectMake(0,0, image.size.width* image.scale, image.size.height* image.scale);
    
  int width = imageRect.size.width;
  int height = imageRect.size.height;
    
  // the pixels will be painted to this array
  uint32_t *pixels = (uint32_t*) malloc(width * height *sizeof(uint32_t));
    
  // clear the pixels so any transparency is preserved
  memset(pixels,0, width * height *sizeof(uint32_t));
    
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    
  // create a context with RGBA pixels
  CGContextRef cOntext= CGBitmapContextCreate(pixels, width, height,8, width *sizeof(uint32_t), colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedLast);
    
  // paint the bitmap to our context which will fill in the pixels array
  CGContextDrawImage(context,CGRectMake(0,0, width, height), [image CGImage]);
    
  for(int y = 0; y 

    [self swizzleMethod:self orgSel:@selector(initWithRed:green:blue:alpha:) swizzSel:@selector(hdd_initWithRed:green:blue:alpha:)];
+ (UIColor *)hdd_colorWithRed:(CGFloat)red green:(CGFloat)green blue:(CGFloat)blue alpha:(CGFloat)a{
  CGFloat gray = red*0.299 + green*0.587 + blue*0.114;
  if ([CSDarkSiteManager isLocalCacheDarkSiteStatus]) {
    return [self hdd_colorWithRed:gray green:gray blue:gray alpha:a];
  }
  else {
    return [self hdd_colorWithRed:red green:green blue:blue alpha:a];
  }
}

+ (void)swizzHook {
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    Method originalMethod = class_getInstanceMethod([self class], @selector(initWithFrame:configuration:));
    Method swizzledMethod = class_getInstanceMethod([self class], @selector(lg_initWithFrame:configuration:));
    method_exchangeImplementations(originalMethod, swizzledMethod);
  });
}
- (instancetype)lg_initWithFrame:(CGRect)frame configuration:(WKWebViewConfiguration *)configuration {
  Class class = NSClassFromString(@"AIRWKWebView");
  if ([CSDarkSiteManager isLocalCacheDarkSiteStatus] && ![self isKindOfClass:class]) {
    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];
    [configuration.userContentController addUserScript:wkUScript];
    WKWebView *webView = [self lg_initWithFrame:frame configuration:configuration];
    return webView;
  }
  else {
    WKWebView *webView = [self lg_initWithFrame:frame configuration:configuration];
    return webView;
  }
  
}