ios开发 根据URL或字符串生成二维码

//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. 将字符串转换成NSData
NSString *urlStr = self.dataDic[@"shareurl"];
NSData *data = [urlStr dataUsingEncoding:NSUTF8StringEncoding];
// 4. 通过KVO设置滤镜inputMessage数据
[filter setValue:data forKey:@"inputMessage"];
// 5. 获得滤镜输出的图像
CIImage *outputImage = [filter outputImage];
// 6. 将CIImage转换成UIImage，并显示于imageView上 (此时获取到的二维码比较模糊,所以需要用下面的createNonInterpolatedUIImageFormCIImage方法重绘二维码)
self.QRcodeContentImageView = [[UIImageView alloc] initWithFrame:CGRectMake((SCREEN_WIDTH-170)/2, CGRectGetMaxY(nameLabel.frame) + 10, 170, 170)];
self.QRcodeContentImageView.image = [self createNonInterpolatedUIImageFormCIImage:outputImage withSize:170];//重绘二维码,使其显示清晰
[self.view addSubview:self.QRcodeContentImageView];

/**
* 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];
}