iOS 合并两张图片(叠加两张图片 重合两张图片)

最近产品给了一个奇葩的需求，需要把一个活动海报和用户生成的二维码合成一张图片，分享出去，效果如下：

创建一个 UIImageView （黑斜体是关键一行代码）

 UIImageView *imgView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 375, 667)];

    imgView.image = [self addImage:[self createImageWithString:@“生成二维码规则”] withImage:@"littlesun"];


    imgView.contentMode = UIViewContentModeScaleAspectFit;
    [self.view addSubview:imgView];

方法实现：

- (UIImage *)addImage:(NSString *)imageName1 withImage:(NSString *)imageName2 {

    UIImage *image1 = [UIImage imageNamed:imageName1];
    UIImage *image2 = [UIImage imageNamed:imageName2];

    UIGraphicsBeginImageContext(image1.size);

    [image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];

    [image2 drawInRect:CGRectMake((image1.size.width - image2.size.width)/2,(image1.size.height - image2.size.height)/2, image2.size.width, image2.size.height)];

    UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return resultingImage;
}

// 生成二维码
- (UIImage *)createImageWithString:(NSString *)string{

    // 1.实例化二维码滤镜
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    // 2.恢复滤镜的默认属性（因为滤镜可能保存上一次的属性）
    [filter setDefaults];

    // 3.讲字符串转换为NSData
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];

    // 4.通过KVO设置滤镜inputMessage数据
    [filter setValue:data forKey:@"inputMessage"];

    // 5.通过了滤镜输出的图像
    CIImage *outputImage = [filter outputImage];

    // 6.因为生成的二维码模糊，所以通过createNonInterpolatedUIImageFormCIImage:outputImage来获得高清的二维码图片
    UIImage *image = [self getErWeiMaImageFormCIImage:outputImage withSize:200];

    return image;
}