- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
/** 1 实例化二维码滤镜 */
CIFilter * filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
/** 2 恢复滤镜默认设置 */
[filter setDefaults];
/** 3 设置二维码内容 */
NSData *data = [@"http://www.baidu.com" dataUsingEncoding:NSUTF8StringEncoding];
[filter setValue:data forKey:@"inputMessage"];
CIImage * outputImage = [filter outputImage];
/** 4 显示二维码 */
self.coreImage.image = [UIImage imageWithCIImage:outputImage];
}