二维码图片生成（扩展知识：创建带圆角效果的图片）

#import <UIKit/UIKit.h>
@interface ViewController : UIViewController
@property (strong, nonatomic) IBOutlet UIImageView *imgVQRCode;

@end

#import "ViewController.h"
#import "KMQRCode.h"
#import "UIImage+RoundedRectImage.h"

@interface ViewController ()
- (void)layoutUI;
@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

[self layoutUI];
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

- (void)layoutUI {
//用于生成二维码的字符串source
NSString *source = @"https://github.com/KenmuHuang";

//使用iOS 7后的CIFilter对象操作，生成二维码图片imgQRCode（会拉伸图片，比较模糊，效果不佳）
CIImage *imgQRCode = [KMQRCode createQRCodeImage:source];

//使用核心绘图框架CG（Core Graphics）对象操作，进一步针对大小生成二维码图片imgAdaptiveQRCode（图片大小适合，清晰，效果好）
UIImage *imgAdaptiveQRCode = [KMQRCode resizeQRCodeImage:imgQRCode
withSize:_imgVQRCode.frame.size.width];

//默认产生的黑白色的二维码图片；我们可以让它产生其它颜色的二维码图片，例如：蓝白色的二维码图片
imgAdaptiveQRCode = [KMQRCode specialColorImage:imgAdaptiveQRCode
withRed:33.0
green:114.0
blue:237.0]; //0~255

//使用核心绘图框架CG（Core Graphics）对象操作，创建带圆角效果的图片
UIImage *imgIcon = [UIImage createRoundedRectImage:[UIImage imageNamed:@"QRCode"]
withSize:CGSizeMake(70.0, 93.0)
withRadius:10];
//使用核心绘图框架CG（Core Graphics）对象操作，合并二维码图片和用于中间显示的图标图片
imgAdaptiveQRCode = [KMQRCode addIconToQRCodeImage:imgAdaptiveQRCode
withIcon:imgIcon
withIconSize:imgIcon.size];

//    imgAdaptiveQRCode = [KMQRCode addIconToQRCodeImage:imgAdaptiveQRCode
//                                              withIcon:imgIcon
//                                             withScale:3];

_imgVQRCode.image = imgAdaptiveQRCode;
//设置图片视图的圆角边框效果
_imgVQRCode.layer.masksToBounds = YES;
_imgVQRCode.layer.cornerRadius = 10.0;
_imgVQRCode.layer.borderColor = [UIColor lightGrayColor].CGColor;
_imgVQRCode.layer.borderWidth = 4.0;
}

@end

#import <UIKit/UIKit.h>

@interface UIImage (RoundedRectImage)
+ (UIImage *)createRoundedRectImage:(UIImage *)image withSize:(CGSize)size withRadius:(NSInteger)radius;

@end

#import "UIImage+RoundedRectImage.h"

@implementation UIImage (RoundedRectImage)

#pragma mark - Private Methods
static void addRoundedRectToPath(CGContextRef contextRef, CGRect rect, float widthOfRadius, float heightOfRadius) {
float fw, fh;
if (widthOfRadius == 0 || heightOfRadius == 0)
{
CGContextAddRect(contextRef, rect);
return;
}

CGContextSaveGState(contextRef);
CGContextTranslateCTM(contextRef, CGRectGetMinX(rect), CGRectGetMinY(rect));
CGContextScaleCTM(contextRef, widthOfRadius, heightOfRadius);
fw = CGRectGetWidth(rect) / widthOfRadius;
fh = CGRectGetHeight(rect) / heightOfRadius;

CGContextMoveToPoint(contextRef, fw, fh/2);  // Start at lower right corner
CGContextAddArcToPoint(contextRef, fw, fh, fw/2, fh, 1);  // Top right corner
CGContextAddArcToPoint(contextRef, 0, fh, 0, fh/2, 1); // Top left corner
CGContextAddArcToPoint(contextRef, 0, 0, fw/2, 0, 1); // Lower left corner
CGContextAddArcToPoint(contextRef, fw, 0, fw, fh/2, 1); // Back to lower right

CGContextClosePath(contextRef);
CGContextRestoreGState(contextRef);
}

#pragma mark - Public Methods
+ (UIImage *)createRoundedRectImage:(UIImage *)image withSize:(CGSize)size withRadius:(NSInteger)radius {
int w = size.width;
int h = size.height;

CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGContextRef contextRef = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpaceRef, (CGBitmapInfo)kCGImageAlphaPremultipliedFirst);
CGRect rect = CGRectMake(0, 0, w, h);

CGContextBeginPath(contextRef);
addRoundedRectToPath(contextRef, rect, radius, radius);
CGContextClosePath(contextRef);
CGContextClip(contextRef);
CGContextDrawImage(contextRef, CGRectMake(0, 0, w, h), image.CGImage);
CGImageRef imageMasked = CGBitmapContextCreateImage(contextRef);
UIImage *img = [UIImage imageWithCGImage:imageMasked];

CGContextRelease(contextRef);
CGColorSpaceRelease(colorSpaceRef);
CGImageRelease(imageMasked);
return img;
}

@end

#import <UIKit/UIKit.h>

@interface KMQRCode : NSObject
+ (CIImage *)createQRCodeImage:(NSString *)source;
+ (UIImage *)resizeQRCodeImage:(CIImage *)image withSize:(CGFloat)size;
+ (UIImage *)specialColorImage:(UIImage*)image withRed:(CGFloat)red green:(CGFloat)green blue:(CGFloat)blue;
+ (UIImage *)addIconToQRCodeImage:(UIImage *)image withIcon:(UIImage *)icon withIconSize:(CGSize)iconSize;
+ (UIImage *)addIconToQRCodeImage:(UIImage *)image withIcon:(UIImage *)icon withScale:(CGFloat)scale;

@end

#import "KMQRCode.h"

@implementation KMQRCode

#pragma mark - Private Methods
void ProviderReleaseData (void *info, const void *data, size_t size){
free((void*)data);
}

#pragma mark - Public Methods
+ (CIImage *)createQRCodeImage:(NSString *)source {
NSData *data = [source dataUsingEncoding:NSUTF8StringEncoding];

CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
[filter setValue:data forKey:@"inputMessage"];
[filter setValue:@"Q" forKey:@"inputCorrectionLevel"]; //设置纠错等级越高；即识别越容易，值可设置为L(Low) |  M(Medium) | Q | H(High)
return filter.outputImage;
}

+ (UIImage *)resizeQRCodeImage:(CIImage *)image withSize:(CGFloat)size {
CGRect extent = CGRectIntegral(image.extent);
CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
size_t width = CGRectGetWidth(extent) * scale;
size_t height = CGRectGetHeight(extent) * scale;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceGray();

CGContextRef contextRef = CGBitmapContextCreate(nil, width, height, 8, 0, colorSpaceRef, (CGBitmapInfo)kCGImageAlphaNone);
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef imageRef = [context createCGImage:image fromRect:extent];
CGContextSetInterpolationQuality(contextRef, kCGInterpolationNone);
CGContextScaleCTM(contextRef, scale, scale);
CGContextDrawImage(contextRef, extent, imageRef);

CGImageRef imageRefResized = CGBitmapContextCreateImage(contextRef);

//Release
CGContextRelease(contextRef);
CGImageRelease(imageRef);
return [UIImage imageWithCGImage:imageRefResized];
}

+ (UIImage *)specialColorImage:(UIImage*)image withRed:(CGFloat)red green:(CGFloat)green blue:(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 colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGContextRef contextRef = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpaceRef, kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
CGContextDrawImage(contextRef, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage);

//Traverse pixe
int pixelNum = imageWidth * imageHeight;
uint32_t* pCurPtr = rgbImageBuf;
for (int i = 0; i < pixelNum; i++, pCurPtr++){
if ((*pCurPtr & 0xFFFFFF00) < 0x99999900){
//Change color
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;
}
}

//Convert to image
CGDataProviderRef dataProviderRef = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, ProviderReleaseData);
CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpaceRef,
kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProviderRef,
NULL, true, kCGRenderingIntentDefault);
CGDataProviderRelease(dataProviderRef);
UIImage* img = [UIImage imageWithCGImage:imageRef];

//Release
CGImageRelease(imageRef);
CGContextRelease(contextRef);
CGColorSpaceRelease(colorSpaceRef);
return img;
}

+(UIImage *)addIconToQRCodeImage:(UIImage *)image withIcon:(UIImage *)icon withIconSize:(CGSize)iconSize {
UIGraphicsBeginImageContext(image.size);
//通过两张图片进行位置和大小的绘制，实现两张图片的合并；其实此原理做法也可以用于多张图片的合并
CGFloat widthOfImage = image.size.width;
CGFloat heightOfImage = image.size.height;
CGFloat widthOfIcon = iconSize.width;
CGFloat heightOfIcon = iconSize.height;

[image drawInRect:CGRectMake(0, 0, widthOfImage, heightOfImage)];
[icon drawInRect:CGRectMake((widthOfImage-widthOfIcon)/2, (heightOfImage-heightOfIcon)/2,
widthOfIcon, heightOfIcon)];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();
return img;
}

+(UIImage *)addIconToQRCodeImage:(UIImage *)image withIcon:(UIImage *)icon withScale:(CGFloat)scale {
UIGraphicsBeginImageContext(image.size);

//通过两张图片进行位置和大小的绘制，实现两张图片的合并；其实此原理做法也可以用于多张图片的合并
CGFloat widthOfImage = image.size.width;
CGFloat heightOfImage = image.size.height;
CGFloat widthOfIcon = widthOfImage/scale;
CGFloat heightOfIcon = heightOfImage/scale;

[image drawInRect:CGRectMake(0, 0, widthOfImage, heightOfImage)];
[icon drawInRect:CGRectMake((widthOfImage-widthOfIcon)/2, (heightOfImage-heightOfIcon)/2,
widthOfIcon, heightOfIcon)];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();
return img;
}

@end