UIScrollView中的图像略有失真

Question

我有一个UIScrollView，里面是UIImageViews所有198 * 198pts。此滚动视图中的图像似乎都略微扭曲。边缘更加锯齿状（我正在使用png文件，图像是卡通/贴纸）。在UIScrollView中未包含的普通UIImageView中，它们看起来很好。谁能给我一些指示，说明为什么会发生这种情况？

UIView *content = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.scrollView.frame.size.width*[self.stickers count], self.scrollView.frame.size.height)];
    for(int i=0; i<[self.stickers count]; i++){

        UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(i*self.scrollView.frame.size.width, 0, self.scrollView.frame.size.width, self.scrollView.frame.size.height)];
        MySticker *sticker = self.stickers[i];
        imageView.image=sticker.image;
        imageView.contentMode=UIViewContentModeScaleAspectFill;
        [content addSubview:imageView];
        //NSLog(@"scroll view width is %f",self.scrollView.frame.size.width);
        //NSLog(@"ImageView width is %f", imageView.frame.size.width);
    }



    self.scrollView.contentSize=CGSizeMake(content.frame.size.width ,content.frame.size.height);
    [self.scrollView addSubview:content];

EDIT ^添加了上面的滚动视图设置