Question

UIImageView *cellimage = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0 , 107, 70)];

The above statement i am sure will make appropriate sizes in both retina resolution devices and standard ones..that is a frame of 107 x 70 pixels on standard and 214 x 140 on retina.

What i want to know is if the below UIGraphicsGetImageFromCurrentImageContext does the same too.. image will be 67 x 67 for standard and 124 x 124 for retina versions?

    CGSize imagesize = CGSizeMake(67, 67);
        UIGraphicsBeginImageContext(imagesize);
        NSLog(@" Converting ");
        [image drawInRect:CGRectMake(0,0,imagesize.width,imagesize.height)];
        newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();  

if not can anyone tell me how to differentiate between models.?
Thanks

Answer 1

You need to use UIGraphicsBeginImageContextWithOptions instead of UIGraphicsBeginImageContext, so that you can specify the scale factor of the image. This will use the scale factor of the device’s main screen:

UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);

This will use the scale factor of the screen containing cellImage, if cellImage is on a screen:

UIGraphicsBeginImageContextWithOptions(imageSize, NO, cellImage.window.screen.scale);

This will hardcode the scale factor:

UIGraphicsBeginImageContextWithOptions(imageSize, NO, 2);