IOS 創建彩色二維碼

因為系統創建的二維碼默認都是黑色的，所以突然想改變一下二維碼顏色，具體操作有點復雜，而且其中用到了好多C語言的語法，Swift不好寫，所以默認用了OC。只貼了.m文件的代碼，.h文件就是幾個類函數的聲明。

#import "UIImage+CreateQRCode.h" 
 
@implementation UIImage (CreateQRCode) 
 
+ (UIImage *)createQRCode:(NSString *)string andSize:(CGSize)size andColor:(UIColor *)color { 
  UIImage *qrcode = [self createNonInterpolatedUIImageFormCIImage:[self createQRForString:string] withSize:size]; 
  const CGFloat *_components = CGColorGetComponents(color.CGColor); 
  CGFloat red = _components[0] * 255.f; 
  CGFloat green = _components[1] * 255.f; 
  CGFloat blue = _components[2] * 255.f; 
  return [self imageBlackToTransparent:qrcode withRed:red andGreen:green andBlue:blue]; 
} 
 
+ (void)setImageViewShadow:(UIImageView *)view { 
  view.layer.shadowOffset = CGSizeMake(0, 2); 
  view.layer.shadowRadius = 2; 
  view.layer.shadowColor = [UIColor blackColor].CGColor; 
  view.layer.shadowOpacity = 0.5; 
  view.backgroundColor = [UIColor clearColor]; 
} 
 
#pragma mark - 創建灰度圖，只有灰度圖才能改變顏色 
+ (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGSize)size { 
  CGRect extent = CGRectIntegral(image.extent); 
  CGFloat scale = MIN(size.width/CGRectGetWidth(extent), size.height/CGRectGetHeight(extent)); 
   
  size_t width = CGRectGetWidth(extent) * scale; 
  size_t height = CGRectGetHeight(extent) * scale; 
   
//  iOS不支持設備依賴顏色空間或通用顏色空間。iOS應用程序必須使用設備顏色空間 
//  設備顏色空間主要用於IOS應用程序，因為其它顏色空間無法在IOS上使用。大多數情況下，Mac OS X應用程序應使用通用顏色空間，而不使用設備顏色空間。 
//  CGColorSpaceCreateDeviceGray：創建設備依賴灰度顏色空間 
//  CGColorSpaceCreateDeviceRGB：創建設備依賴RGB顏色空間 
//  CGColorSpaceCreateDeviceCMYK：創建設備依賴CMYK顏色空間 
  CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();//這個是改變二維碼顏色的主要屬性，必須是灰度空間，作用是將UIImage轉變成了灰度圖 
   
  CGContextRef bitmapRef = CGBitmapContextCreate(NULL, width, height, 8, 0, cs, kCGImageAlphaNone); 
  CIContext * context = [CIContext contextWithOptions:NULL]; 
  CGImageRef bitmapImage = [context createCGImage:image fromRect:extent]; 
  CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationHigh); 
  CGContextScaleCTM(bitmapRef, scale, scale); 
  CGContextDrawImage(bitmapRef, extent, bitmapImage); 
  CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef); 
   
  CGContextRelease(bitmapRef); 
  CGImageRelease(bitmapImage); 
   
  return [UIImage imageWithCGImage:scaledImage]; 
} 
 
#pragma mark - 創建二維碼的主要代碼 
+ (CIImage *)createQRForString:(NSString *)qrString { 
  NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding]; 
  CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"]; 
  [qrFilter setValue:stringData forKey:@"inputMessage"]; 
  [qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"]; 
  return qrFilter.outputImage; 
} 
 
#pragma mark - 改變二維碼的顏色 
void ProviderReleaseData (voidvoid *info, const voidvoid *data, size_t size){ 
  free((void*)data); 
} 
 
+ (UIImage*)imageBlackToTransparent:(UIImage*)image withRed:(CGFloat)red andGreen:(CGFloat)green andBlue:(CGFloat)blue{ 
  const int imageWidth = image.size.width; 
  const int imageHeight = image.size.height; 
  size_t   bytesPerRow = imageWidth * 4; 
  uint32_t* rgbImageBuf = (uint32_t*)malloc(bytesPerRow * imageHeight); 
   
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
  CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace, 
                         kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast); 
  CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage); 
   
  int pixelNum = imageWidth * imageHeight; 
  uint32_t* pCurPtr = rgbImageBuf; 
  for (int i = 0; i < pixelNum; i++, pCurPtr++){ 
    if ((*pCurPtr & 0xFFFFFF00) < 0x99999900){ 
      uint8_t* ptr = (uint8_t*)pCurPtr; 
      ptr[3] = red; //0~255 
      ptr[2] = green; 
      ptr[1] = blue; 
    }else{ 
      uint8_t* ptr = (uint8_t*)pCurPtr; 
      ptr[0] = 0; 
    } 
  } 
   
  CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, ProviderReleaseData); 
  CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpace, 
                    kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider, 
                    NULL, true, kCGRenderingIntentDefault); 
  CGDataProviderRelease(dataProvider); 
  UIImage* resultUIImage = [UIImage imageWithCGImage:imageRef]; 
   
  CGImageRelease(imageRef); 
  CGContextRelease(context); 
  CGColorSpaceRelease(colorSpace); 
   
  return resultUIImage; 
} 
 
@end 

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