生成二維碼圖片，操作如下：
//生成的二維碼
+(UIImage *)getCIIamgeQRCodeGenerator:(NSString *)string{
//創(chuàng)建過濾器
CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
//過濾器恢復(fù)默認(rèn)
[filter setDefaults];
//將NSString格式轉(zhuǎn)化成NSData格式 台谊，如果String 是加密過的 直接使用 String，會導(dǎo)致二維碼無法使用，即使是用對應(yīng)的解碼掃碼也會無法解讀
NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
//給過濾器添加數(shù)據(jù)
[filter setValue:data forKeyPath:@"inputMessage"];
//獲取二維碼過濾器生成的二維碼
CIImage *image = [filter outputImage];
CGRect extent = CGRectIntegral(image.extent);
CGFloat scale = MIN(KMainW/CGRectGetWidth(extent), KMainW/CGRectGetHeight(extent));
// 1.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);
// 2.保存bitmap到圖片
CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
CGContextRelease(bitmapRef);
CGImageRelease(bitmapImage);
//將獲取到的二維碼添加到imageview上
return [UIImage imageWithCGImage:scaledImage];
}
