Issues with sprite location in cocos2d - ios

Question

I have a sprite, that I'd like to use as background image(using cocos2d).
CCSprite *abc =[CCSprite spriteWithImageNamed:#"background.png"];
abc.position = ccp(self.contentSize.width/2,self.contentSize.height/2);
First image is original, second one is a screenshot from the simulator. Resolution of the image is 640/1136. What should I do to fit all space of the screen normally? How schould I locate it?

Answer 1

The code you are using is correct.
The result you are getting is not what you expected because you probably loaded a Retina Image on a non Retina Screen.
Check out Cocos2d Naming conventions here for more info.
For the background image you chose of the sun, I am assuming that you want it to be always in the top right corner. (That makes more sense to me than centering it).
Now an elegant solution to accomplish this would be to get your image for the 4 inch screen that you have already created, and define a rule so that it's top left corner is always at the top left corner of the screen. For the 3.5 inch screens this would be clipped.
Now, first you want to define an anchor point as
_background.anchorPoint = ccp(1.0f, 1.0f);
This will tell Cocos to position your background relative to the top right corner.
Now you can go on and position it so that it is always at the top corner of the screen.
background.position = ccp(self.scene.bounds.size.width, self.scene.size.height);
This would be the standard and best way to do it. Results and benefits:
Works on 3.5 and 4 inch screens without needing specific image sizes
Simple, no unnecessary code and especially UI_INTERFACE_IDIOM testing
The way most everybody does it
Another way of positioning in the top right corner
You can also check out the new positionType property for CCNode in the reference. CCPositionUnitNormalized can help you define a positioning rule similar to saying position this to the 100% width and 100% height of the parent container. It would be something like this.
_background.positionType = CCPositionUnitNormalized;
_background.position = ccp (1.0f, 1.0f);
and have the same result if you prefer this syntax.

Answer 2

You can use either scaling the image to fit the device height or just use separate image for the 4 inch iPhone and 3.5 inch
For Scaling
abc.scaleY = winSize.height/abc.contentSize.height;
For Specific image
if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
{
if([[UIScreen mainScreen] bounds].size.height == 568)
{
// iPhone 5 add different image
}
else
{
// add 3.5 screen image
}
}

Answer 3

I am unsure what "self" is referencing, but I assume it is a layer. It appears you are trying to center the image on the screen, or you need to offset it based on the size of the screen. If so you should get the screen size as it will allow you to place the image properly no matter what the resolution of the screen is. I am using Cocos2d 2.1.
CGSize winSize = [CCDirector sharedDirector].winSize
This is the winSize in points. You can also get the winSize in pixels:
CGSize winSizeInPixels = [CCDirector sharedDirector].winSizeInPixels;
Use whatever works best for you. You can then center the image with the following, for example:
abc.position = ccp(winSize.width / 2, winSize.height / 2);
Regardless of whether or not you are trying to center the image, knowing the screen size will allow you to place the image based on that screen size so that it appears properly.
Obviously the size of the image and whether or not it fills the screen must be addressed.
I hope this helps.