UITabBarItem image size in retina display

I have a TabBarController application that gets all the images from the web, including the icons for the tabBarController. What I want is that images look good when the device has retina display.

This is what I am doing:

1. Resizing down images depending开发者_运维知识库 on the screen scale.
2. Setting the view content scale: imageView.contentsScale = [UIScreen mainScreen].scale;

It is working fine for standard images with UIImageView, however I can not figure out how to do this for UITabBarItems, since I have no access to either the frame or the contentScale.

Any ideas?

Thanks!

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When creating the UIImage, you can set the scale of the image to 2.0 for retina size image resources. Here is a sample of how I did it:

NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:url]];
UIImage *image = [UIImage imageWithData:data];
CGImageRef cgimage = image.CGImage;
image = [UIImage imageWithCGImage:cgimage scale:2.0 orientation:UIImageOrientationUp];

Now you can use this image on your UITabBarItem.

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You can create two versions of the image and name them image.png for the 30px and image@2x.png for the 60px. Then use this:

UIImage *image = [UIImage imageNamed:@"image.png"];

The right resolution image will be loaded depending on the display on the device.

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what about determining whether the device is retina or not, and download different assets accordingly?