Question

While working with xcode, I saw a new line jmUIImage and i try to execute the code in my SDK. But i got a strange Error. The error is

jmUIImage is undeclared

I thought it is a predefined function of Xcode. Is it a predefined or userdefined function?

jmUIImage *buttonImageNormal = [UIImage imageNamed:@"White Button.png"];
    UIImage *stretchableButtonImageNormal = [buttonImageNormal  stretchableImageWithLeftCapWidth:12 topCapHeight:0]

What it indicates and why i got the error ?

Answer 1

It looks like the bug came from the book “Beginning iPhone Development”. On page 85 you can see jmUIImage.

This is just a typo. As you can see in the code the object that is assigned to the jmUIImage instance is just an UIImage. That does not make much sense because you could never use any methods defined in the jmUIImage class on this object.

jmUIImage *buttonImageNormal = [UIImage imageNamed:@"White Button.png"];

If I would encounter such code I would just try it with UIImage.
Another hint for a typo is that the name jmUIImage does not start with a capital letter. And classes (and only classes) should always start with a capital letter in Objective-C.
And when you subclass you should not include the Prefix-Letters in your classname. A proper naming for a subclass of UIImage would be JMImage.

If it smells like a typo and looks like a typo it probably is just a typo.