iOS开发--二维码的生成

 1 - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
 2     
 3     // 0.导入头文件#import <CoreImage/CoreImage.h>
 4     
 5     // 1.创建过滤器 -- 苹果没有将这个字符封装成常量
 6     CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
 7     
 8     // 2.过滤器恢复默认设置
 9     [filter setDefaults];
10     
11     // 3.给过滤器添加数据(正则表达式/帐号和密码) -- 通过KVC设置过滤器,只能设置NSData类型
12     NSString *dataString = @"http://www.baidu.com";
13     NSData *data = [dataString dataUsingEncoding:NSUTF8StringEncoding];
14     [filter setValue:data forKeyPath:@"inputMessage"];
15     
16     // 4.获取输出的二维码
17     CIImage *outputImage = [filter outputImage];
18     
19     // 5.显示二维码
20     self.imageView.image = [UIImage imageWithCIImage:outputImage];
21 }

 1 /**
 2  *  根据CIImage生成指定大小的UIImage
 3  *
 4  *  @param image CIImage
 5  *  @param size  图片宽度
 6  */
 7 - (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size
 8 {
 9     CGRect extent = CGRectIntegral(image.extent);
10     CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
11     
12     // 1.创建bitmap;
13     size_t width = CGRectGetWidth(extent) * scale;
14     size_t height = CGRectGetHeight(extent) * scale;
15     CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
16     CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
17     CIContext *context = [CIContext contextWithOptions:nil];
18     CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
19     CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
20     CGContextScaleCTM(bitmapRef, scale, scale);
21     CGContextDrawImage(bitmapRef, extent, bitmapImage);
22     
23     // 2.保存bitmap到图片
24     CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
25     CGContextRelease(bitmapRef);
26     CGImageRelease(bitmapImage);
27     return [UIImage imageWithCGImage:scaledImage];
28 }