封装成了一个工具类 直接上代码
调用方法:

//根据字符串, 二维码size ,logo图片名称, logosize ,logo 圆角,生成指定二维码的
 self.QRCodeIV.image = [XKQRCodeTool createQRCodeImageWithUrlString:departId QRCodeImageSize:self.QRCodeIV.frame.size logoImageName:@"Icon-40" logoImageSize:CGSizeMake(50, 50) logoImageCornerRadius:14];

.h文件

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <CoreImage/CoreImage.h>
@interface XKQRCodeTool : NSObject

/**
 *  根据字符串, 二维码size ,logo图片名称, logosize ,logo 圆角,生成指定二维码的UIImage
 */
+(UIImage *)createQRCodeImageWithUrlString:(NSString *)urlStr QRCodeImageSize:(CGSize )QRSize logoImageName:(NSString *)logoImageName logoImageSize:(CGSize ) logoSize logoImageCornerRadius:(CGFloat )cornerRadius;

/**
 *  截图
 *
 *  @param view 需要截取的视图
 *
 *  @return 截图 图片
 */
+ (UIImage *)screenShotFormView:(UIView *)view;

/**
 *  读取图片中的二维码
 *
 *  @param image 图片
 *
 *  @return 图片中的二维码数据集合 CIQRCodeFeature对象
 */
+ (NSArray *)readQRCodeFromImage:(UIImage *)image;

@end

.m文件

#import "XKQRCodeTool.h"

@implementation XKQRCodeTool
/**
 *  根据字符串生成二维码 CIImage 对象
 *
 *  @param urlString 需要生成二维码的字符串
 *
 *  @return 生成的二维码
 */
+(CIImage *)creatQRcodeWithUrlstring:(NSString *)urlString{
    // 1.实例化二维码滤镜
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    // 2.恢复滤镜的默认属性 (因为滤镜有可能保存上一次的属性)
    [filter setDefaults];
    // 3.将字符串转换成NSdata
    NSData *data  = [urlString dataUsingEncoding:NSUTF8StringEncoding];
    // 4.通过KVO设置滤镜, 传入data, 将来滤镜就知道要通过传入的数据生成二维码
    [filter setValue:data forKey:@"inputMessage"];
    // 5.生成二维码
    CIImage *outputImage = [filter outputImage];
    return outputImage;
}

/**
 *  改变图片大小 (正方形图片)
 *
 *  @param ciImage 需要改变大小的CIImage 对象的图片
 *  @param size    图片大小 (正方形图片 只需要一个数)
 *
 *  @return 生成的目标图片
 */
+(UIImage *)changeImageSizeWithCIImage:(CIImage *)ciImage andSize:(CGFloat)size{
    CGRect extent = CGRectIntegral(ciImage.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));

    // 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:@{kCIContextUseSoftwareRenderer : @(YES)}];
    CGImageRef bitmapImage = [context createCGImage:ciImage fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    CGContextDrawImage(bitmapRef, extent, bitmapImage);

    // 保存bitmap到图片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);

    return [UIImage imageWithCGImage:scaledImage];
}
/**
 *  根据字符串, 二维码size ,logo图片名称, logosize ,logo 圆角,生成指定二维码的UIImage
 *
 *
 */
+(UIImage *)createQRCodeImageWithUrlString:(NSString *)urlStr QRCodeImageSize:(CGSize )QRSize logoImageName:(NSString *)logoImageName logoImageSize:(CGSize ) logoSize logoImageCornerRadius:(CGFloat )cornerRadius
{

    // 根据字符串生成二维码 CIImage 对象
    CIImage *outputImage = [self creatQRcodeWithUrlstring:urlStr];

    UIImage *QRImage  = [self changeImageSizeWithCIImage:outputImage andSize:QRSize.width]; // 改变二维码的大小
    ;
    UIImageView *imageIV = [[UIImageView alloc]initWithImage:QRImage];
    imageIV.frame = CGRectMake(0, 0, QRSize.width, QRSize.height);

    if ([logoImageName length] > 0) {
        CGFloat logoW = logoSize.width;
        CGFloat logoH = logoSize.height;
        CGFloat logoX = (imageIV.frame.size.width  - logoW )/2;
        CGFloat logoY = (imageIV.frame.size.height - logoH)/2;
        UIImageView *logoIV = [[UIImageView alloc]initWithImage:[UIImage imageNamed:logoImageName]];
        logoIV.frame = CGRectMake(logoX, logoY, logoW, logoH);

        logoIV.layer.cornerRadius = cornerRadius;
        logoIV.clipsToBounds = YES;
        [imageIV addSubview:logoIV];
    }

    UIImage *img = [self screenShotFormView:imageIV];
    return img;

}

/**
 *  截图
 *
 *  @param view 需要截取的视图
 *
 *  @return 截图 图片
 */
+ (UIImage *)screenShotFormView:(UIView *)view
{
    /* size:图像上下文尺寸相当于新的图片尺寸
     opaque:YES ：不透明 No ：透明
     0.0:不需要伸缩
     */
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, 0.0);
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return img;
}

#pragma mark - 读取图片中的二维码
/**
 *  读取图片中的二维码
 *
 *  @param image 图片
 *
 *  @return 图片中的二维码数据集合 CIQRCodeFeature对象
 */
+ (NSArray *)readQRCodeFromImage:(UIImage *)image{
    // 创建一个CIImage对象
    CIImage *ciImage = [[CIImage alloc] initWithCGImage:image.CGImage options:nil];
    CIContext *context = [CIContext contextWithOptions:@{kCIContextUseSoftwareRenderer : @(YES)}]; // 软件渲染
    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:context options:@{CIDetectorAccuracy : CIDetectorAccuracyHigh}];// 二维码识别
    // 注意这里的CIDetectorTypeQRCode
    NSArray *features = [detector featuresInImage:ciImage];
    NSLog(@"features = %@",features); // 识别后的结果集
    for (CIQRCodeFeature *feature in features) {
        NSLog(@"msg = %@",feature.messageString); // 打印二维码中的信息
    }
    return features;
}
@end