生成二维码
常见应用是我的二维码，然后就是一张二维码图片，展示出来，让人家扫描
先生成CIImage
/**
* 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 *)createQRcodeWithUrlString:(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;
}
然后合成UIImage
/**
* 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];
}
合成一个对外接口
+ (UIImage *)createWithUrlString:(NSString *)urlString size:(CGFloat)size {
if ((urlString == nil) || [urlString isEqualToString:@""]) {
return nil;
}
if (size <= 0 ) {
return nil;
}
CIImage *ci = [KJTQrGenerate createQRcodeWithUrlString:urlString];
return [KJTQrGenerate createNonInterpolatedUIImageFormCIImage:ci withSize:size];
}
这里的
size是指width和height相等的正方形
识别二维码
常见的场景是长按二维码图片，识别二维码内容
+ (NSString *)stringFromImage:(UIImage *)image {
if (image == nil) {
return nil;
}
// 创建 CIDetector，并设定识别类型：CIDetectorTypeQRCode
CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{CIDetectorAccuracy: CIDetectorAccuracyHigh}];
// 获取识别结果
NSArray *features = [detector featuresInImage:[CIImage imageWithCGImage:image.CGImage]];
if (features.count == 0) {
return nil;
} else {
NSString *resultString = nil;
for (int index = 0; index < [features count]; index ++) {
CIQRCodeFeature *feature = [features objectAtIndex:index];
resultString = feature.messageString;
}
return resultString;
}
}
