Converting imageNamed to imageWithContentsOfFile: - ios

Question

My code for my images is
-(IBAction)start:(id)sender
{
animation.animationImages = [NSArray arrayWithObjects:
[UIImage imageNamed:#"Paddle 1.png"],
[UIImage imageNamed:#"Paddle 2.png"],
[UIImage imageNamed:#"Paddle 3.png"],
[UIImage imageNamed:#"Paddle 4.png"],
nil];
[animation setAnimationRepeatCount:0];
animation.animationDuration = 2.5;
[animation startAnimating];
}
This is caching too much memory and I was told in a previous question to swap my code to using
[UIImage imageWithContentsOfFile: GetImgWithoutCaching(#"Paddle 1.jpg")]
and
UIImage* GetImgWithoutCaching(NSString* imgName)
{
NSString *imagePath = [[NSBundle mainBundle] pathForResource:imgName ofType:nil];
return [UIImage imageWithContentsOfFile:imagePath];
}
What is the correct way of writing the code? do i place that code in my .m as is?

Answer 1

First you should check if using retina picture:
BOOL isHighResolution = NO;
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)]) {
if ([UIScreen mainScreen].scale > 1) {
isHighResolution = YES;
}
}
if you are using retina picture, add #2x to image name, like this:
NSString *noExtFileName = [name stringByDeletingPathExtension];
if (isHighResolution) {
if (![noExtFileName hasSuffix:#"#2x"]) {
noExtFileName = [noExtFileName stringByAppendingString:#"#2x"];
}
}
//if image only "png" type
return [[NSBundle mainBundle] pathForResource:noExtFileName ofType:#"png"];

Answer 2

Since your GetImgWithoutCaching function returns a UIImage you would need:
-(IBAction)start:(id)sender
{
animation.animationImages = [NSArray arrayWithObjects:
GetImgWithoutCaching(#"Paddle 1.jpg"),
GetImgWithoutCaching(#"Paddle 2.jpg"),
GetImgWithoutCaching(#"Paddle 3.jpg"),
GetImgWithoutCaching(#"Paddle 4.jpg"),
nil];
[animation setAnimationRepeatCount:0];
animation.animationDuration = 2.5;
[animation startAnimating];
}