iOS开发之----生成二维码

- (void)viewDidLoad {
[super viewDidLoad];

/*
注意:
1.生成二维码时, 不建议让二维码保存过多数据, 因为数据越多, 那么二维码就越密集,那么扫描起来就越困难
2.二维码有三个定位点, 着三个定位点不能被遮挡, 否则扫描不出来
3.二维码即便缺失一部分也能正常扫描出结果, 但是需要注意, 这个缺失的范围是由限制的, 如果太多那么也扫面不出来
*/
// 1.创建滤镜
CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
// 2.还原滤镜默认属性
[filter setDefaults];
// 3.将需要生成二维码的数据转换为二进制
NSData *data = [@"123" dataUsingEncoding:NSUTF8StringEncoding];
// 4.给滤镜设置数据
[filter setValue:data forKeyPath:@"inputMessage"];
// 5.生成图片
CIImage *qrcodeImage =  [filter outputImage];

// 6.显示图片
//    self.qrcodeImageView.image = [UIImage imageWithCIImage:qrcodeImage];
//    self.qrcodeImageView.image = [self createNonInterpolatedUIImageFormCIImage:qrcodeImage withSize:600];

UIImage *bg = [self createNonInterpolatedUIImageFormCIImage:qrcodeImage withSize:600];
UIImage *icon = [UIImage imageNamed:@"icon"];
self.qrcodeImageView.image = [self creteImageWithBg:bg icon:icon];
}

- (UIImage *)creteImageWithBg:(UIImage *)bg icon:(UIImage *)icon
{
// 1.创建图形上下文
UIGraphicsBeginImageContextWithOptions(bg.size, YES, 0.0);
// 2.绘制背景
[bg drawInRect:CGRectMake(0, 0, bg.size.width, bg.size.height)];
// 3.绘制图标
CGFloat iconW = 60;
CGFloat iconH = 60;
CGFloat iconX = (bg.size.width - iconW) * 0.5;
CGFloat iconY = (bg.size.height - iconH) * 0.5;
[icon drawInRect:CGRectMake(iconX, iconY, iconW, iconH)];
// 4.取出图片
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
// 5.关闭上下文
UIGraphicsEndImageContext();

// 5.返回图片
return newImage;
}

/**
*  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];
}