个人中心高斯模糊

简单的在背景的图片上放一个高斯图层，背景图片和头像数据源一样，就是等比放大。

        [_headImgView sd_setImageWithURL:[NSURL URLWithString:@""] placeholderImage:_IMG(@"DefaultHeader")];
        // 高斯背景图
        UIImageView * imageView = [[UIImageView alloc] initWithFrame:CGRectMake(-frame.size.width/2, -frame.size.height/2, frame.size.width*2, frame.size.height*3/2)];
        imageView.contentMode = UIViewContentModeScaleAspectFit;
        [imageView sd_setImageWithURL:[NSURL URLWithString:@""] placeholderImage:_IMG(@"ProMineBGImg")];
        
        UIVisualEffectView * visualEffectView = [[UIVisualEffectView alloc] initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleLight]];
        visualEffectView.frame = CGRectMake(0, 0, imageView.frame.size.width, imageView.frame.size.height);
        [imageView addSubview:visualEffectView];
        [self addSubview:imageView];
        [self sendSubviewToBack:imageView];