系统原生自带的生成二维码

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@end

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic)UIImageView *qrcodeImageView;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

self.qrcodeImageView = [[UIImageView alloc]initWithFrame:CGRectMake(40, 60, 220, 220)];

UIImage *qrcode = [self createNonInterpolatedUIImageFormCIImage:[self createQRForString:@"www.baidu.com"] withSize:250.0f];

UIImage *customQrcode = [self imageBlackToTransparent:qrcode withRed:60.0f andGreen:74.0f andBlue:89.0f];

self.qrcodeImageView.image = customQrcode;

// set shadow

//self.qrcodeImageView.layer.shadowOffset = CGSizeMake(0, 0);

self.qrcodeImageView.layer.shadowRadius = 0;

self.qrcodeImageView.layer.shadowColor = [UIColor cyanColor].CGColor;

self.qrcodeImageView.layer.shadowOpacity = 1;

[self.view addSubview:self.qrcodeImageView];

}

#pragma mark - InterpolatedUIImage

//因为生成的二维码是一个CIImage，我们直接转换成UIImage的话大小不好控制，所以使用下面方法返回需要大小的UIImage

- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size {

CGRect extent = CGRectIntegral(image.extent);

CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));

// create a bitmap image that we'll draw into a bitmap context at the desired size; // 创建bitmap;

size_t width = CGRectGetWidth(extent) * scale;

size_t height = CGRectGetHeight(extent) * scale;

CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();

CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);

CIContext *context = [CIContext contextWithOptions:nil];

CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];

CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);

CGContextScaleCTM(bitmapRef, scale, scale);

CGContextDrawImage(bitmapRef, extent, bitmapImage);

// Create an image with the contents of our bitmap // 保存bitmap到图片

CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);

// Cleanup

CGContextRelease(bitmapRef);

CGImageRelease(bitmapImage);

return [UIImage imageWithCGImage:scaledImage];

}

#pragma mark - QRCodeGenerator

//首先是二维码的生成，使用CIFilter很简单，直接传入生成二维码的字符串即可：

- (CIImage *)createQRForString:(NSString *)qrString {

// Need to convert the string to a UTF-8 encoded NSData object

NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding];

// Create the filter 创建filter

CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

// Set the message content and error-correction level // 设置内容和纠错级别

[qrFilter setValue:stringData forKey:@"inputMessage"];

[qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];

// Send the image back 返回CIImage

return qrFilter.outputImage;

}

#pragma mark - imageToTransparent

//因为生成的二维码是黑白的，所以还要对二维码进行颜色填充，并转换为透明背景，使用遍历图片像素来更改图片颜色，因为使用的是CGContext，速度非常快：

void ProviderReleaseData (void *info, const void *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);

// create context

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace,

kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);

CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage);

// traverse pixe // 遍历像素

int pixelNum = imageWidth * imageHeight;

uint32_t* pCurPtr = rgbImageBuf;

for (int i = 0; i < pixelNum; i++, pCurPtr++){

if ((*pCurPtr & 0xFFFFFF00) < 0x99999900){ // 将白色变成透明

// 改成下面的代码，会将图片转成想要的颜色

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;

}

}

// context to image 输出图片

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];

// release 清理空间

CGImageRelease(imageRef);

CGContextRelease(context);

CGColorSpaceRelease(colorSpace);

return resultUIImage;

}