如何利用Xcode自带的方法生成二维码

#import <CoreImage/CoreImage.h>

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

// 1.实例化二维码滤镜
CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

// 2.恢复滤镜的默认属性
[filter setDefaults];

// 3.二维码信息
NSString *str = @"哎呀我去"; // 展示一串文字
//    NSString *str = @"http://www.baidu.com"; // 直接打开网页

// 4.将字符串转成二进制数据
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];

// 5.通过KVC设置滤镜inputMessage数据
[filter setValue:data forKey:@"inputMessage"];

// 6.获取滤镜输出的图像
CIImage *outputImage = [filter outputImage];

// 7.将CIImage转成UIImage
UIImage *image = [self createNonInterpolatedUIImageFormCIImage:outputImage withSize:200];

// 8.展示二维码
self.imageView.image = image;
}使用前需导入#import <CoreImage/CoreImage.h>

/**
*  根据CIImage生成指定大小的UIImage
*
*  @param image CIImage
*  @param size  图片宽度
*/
- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size
{
CGRect extent = CGRectIntegral(image.extent);
CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));

// 1.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);

// 2.保存bitmap到图片
CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
CGContextRelease(bitmapRef);
CGImageRelease(bitmapImage);
return [UIImage imageWithCGImage:scaledImage];
}