iOS整个APP实现灰色主题的示例代码

灰色主题

背景

在一些哀悼日，清明节的时候app会实现一些灰色主题功能，部分app需求是tab首页实现灰色模式就可以，但一些需求是直接整个app都变为灰色模。

普通UI界面
web页面
xib界面
attributeText加载的htmlString页面
attachment挂件页面

实现方式

基本的实现方式1，普通页面用hook颜色方式2.web页面用注入灰色js实现方式

图片变灰

重新绘制图片变为灰色代码实现

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									//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 < height; y++) {

									    for(int x = 0; x < width; x++) {

									      uint8_t *rgbaPixel = (uint8_t*) &pixels[y * width + x];

									      // convert to grayscale using recommended method: http://en.wikipedia.org/wiki/Grayscale#Converting_color_to_grayscale

									      uint32_t gray = 0.3 * rgbaPixel[RED] +0.59 * rgbaPixel[GREEN] +0.11 * rgbaPixel[BLUE];

									      // set the pixels to gray

									      rgbaPixel[RED] = gray;

									      rgbaPixel[GREEN] = gray;

									      rgbaPixel[BLUE] = gray;

									    }

									  }

									  // create a new CGImageRef from our context with the modified pixels

									  CGImageRef imageRef = CGBitmapContextCreateImage(context);

									  // we're done with the context, color space, and pixels

									  CGContextRelease(context);

									  CGColorSpaceRelease(colorSpace);

									  free(pixels);

									  // make a new UIImage to return

									  UIImage *resultUIImage = [UIImage imageWithCGImage:imageRef scale:image.scale orientation:UIImageOrientationUp];

									  // we're done with image now too

									  CGImageRelease(imageRef);

									  return resultUIImage;

									}

文本变灰

文本textColor变为灰色 rgb的处理有很多这里简单提供一个

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									    [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];

									  }

									}

文本变灰色还牵扯到系统颜色的灰色处理，例如[UIcolor whiteColor],系统alertView弹框中的蓝色按钮颜色处理，都需要有专门的处理方法

xib图片变灰

由于xib读取图片不是直接通过[UIimageView imageName:@""] 加载方式没办法直接通过hook setImage直接设置xib图片变为灰色

方法：重写UIimageView的awakeFromNib，再去执行hook setImage的方法进行加载

webView的变灰

hook webView的初始化方法，注入js灰色

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									+ (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;

									  }

									}