设置图片加载进度条

[self.picImage sd_setImageWithURL:[NSURL URLWithString:self.model.pic] placeholderImage:PLACEPIC];        [self.picImage sd_setImageWithURL:[NSURL URLWithString:self.model.pic] placeholderImage:nil options:0 progress:^(NSInteger receivedSize, NSInteger expectedSize) {            self.progress.progress = (double)receivedSize / expectedSize;        } completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {            [self.progress removeFromSuperview];            self.progress = nil;        }];