第一步：

使用cocoapods第三方庫管理工具匯入libqrencode第三方庫
注：libqrencode實際是UIImageView的分類

第二步：

建立一個QRCodeGenerator的類
.h檔案：
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface QRCodeGenerator : NSObject
+ (UIImage *)qrImageForString:(NSString *)string imageSize:(CGFloat)size;
@end

.m檔案

#import "QRCodeGenerator.h"
#import <qrencode.h>
enum {
qr_margin = 3
};
@implementation QRCodeGenerator

+ (void)drawQRCode:(QRcode *)code context:(CGContextRef)ctx size:(CGFloat)size {
unsigned char *data = 0;
int width;
data = code->data;
width = code->width;
float zoom = (double)size / (code->width + 2.0
 
 * qr_margin);
CGRect rectDraw = CGRectMake(0, 0, zoom, zoom);
// draw
CGContextSetFillColor(ctx, CGColorGetComponents([UIColor blackColor].CGColor));
for(int i = 0; i < width; ++i) {
for(int j = 0; j < width; ++j) {
if(*data & 1) {
rectDraw.origin = CGPointMake((j + qr_margin) * zoom,(i + qr_margin) * zoom);
CGContextAddRect(ctx, rectDraw);
}
++data;
}
}
CGContextFillPath(ctx);
}

+ (UIImage
 
 *)qrImageForString:(NSString *)string imageSize:(CGFloat)size {
if (![string length]) {
return nil;
}
QRcode *code = QRcode_encodeString([string UTF8String], 0, QR_ECLEVEL_L, QR_MODE_8, 1);
if (!code) {
return nil;
}
// create context
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(0, size, size, 8, size * 4, colorSpace, kCGImageAlphaPremultipliedLast);
CGAffineTransform translateTransform = CGAffineTransformMakeTranslation(0, -size);
CGAffineTransform scaleTransform = CGAffineTransformMakeScale(1, -1);
CGContextConcatCTM(ctx, CGAffineTransformConcat(translateTransform, scaleTransform));
// draw QR on this context
[QRCodeGenerator drawQRCode:code context:ctx size:size];
// get image
CGImageRef qrCGImage = CGBitmapContextCreateImage(ctx);
UIImage * qrImage = [UIImage imageWithCGImage:qrCGImage];
// some releases
CGContextRelease(ctx);
CGImageRelease(qrCGImage);
CGColorSpaceRelease(colorSpace);
QRcode_free(code);
return qrImage;
}
@end

第三步：

在需要生成本地二維碼的類中匯入QRCodeGenerator該類，列：#import "QRCodeGeneratir.h"

第四步：

使用qrImageForString方法生成二維碼
例如(第一個引數為二維碼中包含的資料,第二個引數為二維碼的大小)：
self.QRCodeimageView.image = [QRCodeGenerator qrImageForString:jsonStr imageSize:200];