iOS How to compare two UIImage objects?

[Sergio10]

Hi,

I have two objects: image1 and image2 with UIImage type.

Need to know are they init with "myImage.png" or not.
How to compare?
Could you please provide the code?

Thanks.

 

[Eraserhead]

You could try hashing, though its an inexact science. I would suggest using NSObject's isEqual: but I guess they won't be the same object, just two objects referencing the same file.

 

[Sergio10]

IsEqual doesn't compare(
I wrote:

UIImage *image1 = [UIImage imageNamed: @"myImage.png"];
UIImage *image2 = [UIImage imageNamed: @"myImage.png"];

if([someImage isEqualTo: patternImage])   // never true (((
{
           // some code
}

So, How to know that my UIImage objects initialized with the same image?
Please provide me a code.
Thanks.

 

[Eraserhead]

What research have you already done on this?

You can't just expect free code and that will help round down the location of a solution.

 

[Sergio10]

So,

I suggest to get pixel data(using CGImage) and compare it. How ti do it?

 

[kainjow]

imageNamed: returns a cached object, so for basic purposes you could just try checking the pointers:

if (image1 == image2)

If that doesn't work you could cache the image objects yourself and then compare.

Other than that, you'll have to do some pixel comparisons which won't be pretty.

 

[Sergio10]

So,

I suggest to get pixel data(using CGImage) and compare it. How ti do it?

 

[PhoneyDeveloper]

Forget about comparing pixels.

UImage doesn't keep a name of the file it was inited with. You need to do that part yourself. You could subclass UIImage and add a name property to it. Compare the names to find if they're the same.

Else, you can keep your own dictionary that uses the UIImage* as the key and the name as value. Or keep a couple mutable arrays with UIImages and names as the values.