Setting retina background images appear zoomed in

Question

I'm setting a random background image for my app by loading an image and adding it to my view:

UIImageView *background = [[UIImageView alloc] 
                               initWithImage:[UIImage imageNamed:
                               [NSString stringWithFormat:@"bg%u.jpg", 1+arc4random_uniform(15)]]];
    [self.view addSubview:background];
    [self.view sendSubviewToBack:background];

My images are 640x1136 at 326 ppi, yet the image is appearing zoomed in for some reason. Any ideas as to why would be appreciated.

Simulator

Actual image:

Thanks.

@b3ginneriOS converting to a png didn't appear to work at all unfortunately. — Nick Triantafillou, Sep 23 '13 at 08:53
@Spynet this worked perfectly. Thank you! can you add it as an answer and I'll accept it. — Nick Triantafillou, Sep 23 '13 at 08:54
@Nick how you are naming retina and non retina images. Non-retina image should follow convention like "imageName.png " and retina image should follow convention like "imageName@2x.png " . If you does like this iOS itself picks image based on device resolution — Vinodh, Sep 23 '13 at 11:32

Magyar Miklós · Accepted Answer · 2013-09-23T09:04:55.940

1

It s because you alloc init with your image, not with a fix size.

int screenHeight = [UIScreen mainScreen].bounds.size.height;
int screenWidth = [UIScreen mainScreen].bounds.size.width;


UIImageView *background = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, screenWidth, screenHeight)];

background.image = [UIImage imageNamed:[NSString stringWithFormat:@"bg%u.jpg",1+arc4random_uniform(15)]]

[self.view addSubview:background];
[self.view sendSubviewToBack:background];

Do it like this

edited Sep 23 '13 at 09:04

answered Sep 23 '13 at 08:59

Magyar Miklós

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what is screenWidth and screenHeight ? – Arun Sep 23 '13 at 09:03
changed answer to this based on the assumption that you're correct about downsampling, though the images look the same on the iphone screen (maybe it's too small to see). It works after your edits. Thanks. – Nick Triantafillou Sep 23 '13 at 09:22
This answer is not from me, and this solution is not any different than that of spynet! In fact, i think i might have been wrong (i was testing a couple of things) – micantox Sep 23 '13 at 09:40
I don't see a solution from you at all, just comments that none of them are correct. – Nick Triantafillou Sep 23 '13 at 09:45

score 0 · Answer 2 · answered Sep 23 '13 at 08:58

0

Hi try like this,

UIImageView *background = [[UIImageView alloc] 
                               initWithImage:[UIImage imageNamed:
                               [NSString stringWithFormat:@"bg%u.jpg", 1+arc4random_uniform(15)]]];

    background.frame = self.view.frame; // this is the only line you have missed 
    [self.view addSubview:background];
    [self.view sendSubviewToBack:background];

answered Sep 23 '13 at 08:58

Arun

3,406
4
30
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This is not the right solution. The image will be downsampled and it will look just like what it would look on a non-retina phone. – micantox Sep 23 '13 at 09:02
i'm testing this on an iPhone5 and the images appear high resolution, any ideas? – Nick Triantafillou Sep 23 '13 at 09:05
I don't know about downsample( or Spynet code is not good ), but I know that, my answer is correct. – Magyar Miklós Sep 23 '13 at 09:12
@micantox what is downsampled ? – Arun Sep 23 '13 at 09:19

Setting retina background images appear zoomed in

2 Answers2