/**
 *  生成二維碼
 */
+ (UIImage *)creatCIQRCodeImage:(NSString *)dataStr{
    //創(chuàng)建過濾器，這里的@"CIQRCodeGenerator"是固定的
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    //恢復(fù)默認(rèn)設(shè)置
    [filter setDefaults];
    //給過濾器添加數(shù)據(jù)
    NSData *data = [dataStr dataUsingEncoding:NSUTF8StringEncoding];
    //value必須是NSData類型
    [filter setValue:data forKeyPath:@"inputMessage"];
    //生成二維碼
    CIImage *outputImage = [filter outputImage];
    //顯示二維碼
    return [self creatNonInterpolatedUIImageFormCIImage:outputImage withSize:100.0];
}

+ (UIImage *)creatNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat)size {
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    //創(chuàng)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);
    //保存bitmap圖片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}