Resize UIImageView in UITableViewCell

Question

I have a 16x16 pixel image that I want to display in an UIImageView. So far, no problem, however 16x16 is a bit small so I want to resize the image view to 32x32 and thus also scale the image up. But I can't get it to work, it always shows the image with 16x16, no matter what I try. I googled a lot, and found many snippets here on Stack Overflow, but its still doesn't work. Here is my code so far:

[[cell.imageView layer] setMagnificationFilter:kCAFilterNearest];
[cell.imageView setAutoresizingMask:UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight];
[cell.imageView setClipsToBounds:NO];
[cell.imageView setFrame:CGRectMake(0, 0, 32, 32)];
[cell.imageView setBounds:CGRectMake(0, 0, 32, 32)];
[cell.imageView setImage:image];

I don't want to create a new 32x32 pixel image because I already have some memory problems on older devices and creating two images instead of having just one looks like a very bad approach to me (the images can be perfectly scaled and it doesn't matter if they lose quality).

Answer 1

I have successfully made it using CGAffineTransformMakeScale!

cell.imageView.image = cellImage;
//self.rowWidth is the desired Width
//self.rowHeight is the desired height
CGFloat widthScale = self.rowWidth / cellImage.size.width;
CGFloat heightScale = self.rowHeight / cellImage.size.height;
//this line will do it!
cell.imageView.transform = CGAffineTransformMakeScale(widthScale, heightScale);

Answer 2

I think you need to set the contentMode:

cell.imageView.contentMode = UIViewContentModeScaleAspectFit;

In context:

UIImage *image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"slashdot" ofType:@"png"]];
imageView = [[UIImageView alloc] initWithImage:image];
[imageView setBackgroundColor:[UIColor greenColor]];
[imageView setFrame:CGRectMake(x,y,32,32)];
imageView.contentMode = UIViewContentModeScaleAspectFit;    
[self.view addSubview:imageView];

Note: I've set a background colour so you can debug the on-screen boundaries of the UIImageView. Also x and y are arbitrary integer coordinates.

Answer 3

Using CGAffineTransformMakeScele as @ahmed said is valid and do not seems to be duck type solution at al! For instance, if you have a large image and put it into a UITableViewCell (say the image is 2x larger than the one that fits into a table cell. If you scale by 0.9 you don't see any result. Only if you scale by less than 0.5 (because 0.5*2.0 = 1.0 that is the size of the cell). So it seems that inside the api, apple is doing exactly that.