IOS 创建彩色二维码实例详解

#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 - 创建灰度图，只有灰度图才能改变颜色 + (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不支持设备依赖颜色空间或通用颜色空间。iOS应用程序必须使用设备颜色空间 //  设备颜色空间主要用于IOS应用程序，因为其它颜色空间无法在IOS上使用。大多数情况下，Mac OS X应用程序应使用通用颜色空间，而不使用设备颜色空间。 //  CGColorSpaceCreateDeviceGray：创建设备依赖灰度颜色空间 //  CGColorSpaceCreateDeviceRGB：创建设备依赖RGB颜色空间 //  CGColorSpaceCreateDeviceCMYK：创建设备依赖CMYK颜色空间   CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();//这个是改变二维码颜色的主要属性，必须是灰度空间，作用是将UIImage转变成了灰度图      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 - 创建二维码的主要代码 + (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 - 改变二维码的颜色 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