iOS WKWebview 白屏检查方法（OC）

+(UIImage *)scaleImage: (UIImage *)image {
    CGFloat scale = 1.0;
    CGSize newsize;
    newsize.width = floor(image.size.width * scale);
    newsize.height = floor(image.size.height * scale);
    if (@available(iOS 10.0, *)) {
        UIGraphicsImageRenderer * renderer = [[UIGraphicsImageRenderer alloc] initWithSize:newsize];
          return [renderer imageWithActions:^(UIGraphicsImageRendererContext * _Nonnull rendererContext) {
              [image drawInRect:CGRectMake(0, 0, newsize.width, newsize.height)];
          }];
    }else{
        return image;
    }
}
+(BOOL)searchEveryPixel:(UIImage *)image {
    CGImageRef cgImage = [image CGImage];
    size_t width = CGImageGetWidth(cgImage);
    size_t height = CGImageGetHeight(cgImage);
    size_t bytesPerRow = CGImageGetBytesPerRow(cgImage); //每个像素点包含r g b a 四个字节
    size_t bitsPerPixel = CGImageGetBitsPerPixel(cgImage);

    CGDataProviderRef dataProvider = CGImageGetDataProvider(cgImage);
    CFDataRef data = CGDataProviderCopyData(dataProvider);
    UInt8 * buffer = (UInt8*)CFDataGetBytePtr(data);

    int whiteCount = 0;
    int totalCount = 0;

    for (int j = 0; j < height; j ++ ) {
        for (int i = 0; i < width; i ++) {
            UInt8 * pt = buffer + j * bytesPerRow + i * (bitsPerPixel / 8);
            UInt8 red   = * pt;
            UInt8 green = *(pt + 1);
            UInt8 blue  = *(pt + 2);

            totalCount ++;
            if (red == 255 && green == 255 && blue == 255) {
                whiteCount ++;
            }
        }
    }
    float proportion = (float)whiteCount / totalCount ;
    NSLog(@"当前像素点数：%d,白色像素点数:%d , 占比: %f",totalCount , whiteCount , proportion );
    if (proportion > 0.95) {
        return YES;
    }else{
        return NO;
    }
}