生成二維碼

• 我們簡單的使用一下CIFilter來完成二維碼的生成，解剖一下二維碼的生成過程

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• 查找到 kCICategoryBuiltIn 內建的濾鏡名

NSArray *filterNames = [CIFilter filterNamesInCategory:kCICategoryBuiltIn];

    NSLog(@"%@",filterNames);

• 找到這個CIQRCodeGenerator

@property (nonatomic, strong) CIFilter *filter;
 _filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

   NSArray *inputKeys =  _filter.inputKeys;

• inputMessage 表示 二維碼的內容, 參數類型是NSData

 NSData *data =  [content dataUsingEncoding:NSUTF8StringEncoding];
    [_filter setValue:data forKey:@"inputMessage"];

   CIImage *ciImage =  _filter.outputImage;
  ciImage =   [ciImage imageByApplyingTransform:CGAffineTransformMakeScale(10, 10)];
    UIImage *image = [UIImage imageWithCIImage:ciImage];

  image =   [image imageWithIcon:[UIImage imageNamed:@"wohao"]];
    self.imageView.image = image;

• 給UIImage 寫一個分類

- (UIImage *)imageWithIcon:(UIImage *)icon
{
    //開啓上下文
    UIGraphicsBeginImageContext(self.size);
    //畫原圖
    [self drawInRect:CGRectMake(0, 0, self.size.width, self.size.height)];

    //在中間畫用戶頭像，寬高爲20%，正方形
    CGFloat WH = MIN(self.size.width, self.size.height) * 0.2;
    [icon drawInRect:CGRectMake((self.size.width - WH) * 0.5, (self.size.height - WH) * 0.5, WH, WH)];

   UIImage *newImage =  UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;

}

畫一個頭像上去，看一下效果：