图片模糊处理

1、UIToolbar 模糊效果不受控制

    UIToolbar *blurView = [[UIToolbar alloc] init];
    blurView.barStyle = UIBarStyleBlack;
    [_headImgView addSubview:blurView];

2、高斯模糊处理

+(UIImage *)coreBlurImage:(NSString *)imageUrl withPlaceholderImage:(UIImage *)plaImg withBlurNumber:(CGFloat)blur
{
    UIImage *changeImg;
    if(imageUrl.length > 0)//网络图片
    {
        NSURL *url =[NSURL URLWithString:imageUrl];
        NSData *tempData =[NSData dataWithContentsOfURL:url];
        changeImg = [UIImage imageWithData:tempData]; // 取得图片
    }
    else//本地图片
    {
        changeImg = plaImg;
    }
    
    
    CIContext *context = [CIContext contextWithOptions:nil];
    CIImage *inputImage= [CIImage imageWithCGImage:changeImg.CGImage];
    //设置filter
    CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
    [filter setValue:inputImage forKey:kCIInputImageKey];
    [filter setValue:@(blur) forKey: @"inputRadius"];
    //模糊图片
    CIImage *result=[filter valueForKey:kCIOutputImageKey];
//    CGImageRef outImage=[context createCGImage:result fromRect:[result extent]];
   CGImageRef outImage = [context createCGImage: result fromRect:[inputImage extent]];
    UIImage *blurImage=[UIImage imageWithCGImage:outImage];
    CGImageRelease(outImage);
    return blurImage;
}