iOS Understanding pointers basics

[doanelinde]

I have a basic understanding of pointers from C.

One thing that confused me for a while in objc with pointers was the fact that there was no dereferencing character being used, but I wasn't aware that that was what was confusing me, if that makes sense!

I think I've got a grip on that now.

But I'm still having a lot of issues with pointers and variables.

For instance I have a class with a list of properties, such as:

	NSInteger atmID;
	NSNumber *Latitude;
	NSNumber *Longitude;
	NSString *Add1; 
	NSString *Add2;
	NSString *Add3;

To me, this is a list of variables of different types. But there's some massive difference between the way the different types are working. And let's say I throw in a primitive C long there as well.

So Latitude is a pointer to a variable of type NSNumber? But NSInteger isn't a pointer, and when I @property it, I can't retain it, I simply assign it.
I've had no issues whatsoever working with the strings, but I have had issues working with integers and other variables.

These are really confusing me, and to be honest I just don't know what questions to ask. I've looked around and found a lot of information on pointers but still can't get my head around them.

Any help would be greatly appreciated, thanks in advance.

 

[robbieduncan]

Look at the documentation for NSInteger: it's not a class: it's typedefed type. That is the difference.

 

[dejo]

Also, the convention is to name your variables starting with a lower-case letter. Helps distinguish them from class names, which normally start with upper-case.

 

[doanelinde]

Yes, I looked at that before and from my understanding NSInteger is either a long or an int as from primitive c, depending on whether a 32 or 64bit variable is needed?

But I still don't understand the difference between these variables and pointers.

What's the difference between an NSString and an int as attributes of my object?


The reason I have these in upper case is because the names have to match the elements from an XML file I'm parsing in.


Thanks for the help!

 

[dejo]

What's the difference between an NSString and an int as attributes of my object?

NSString is a class and int is a C primitive. The former is an Objective-C construct and the latter is a C construct. If that confuses you, perhaps avoid the C primitives and use NSNumber instead of int.

 

[Kingbombs]

maybe look at the relation of an array and a pointer, it may help you to understand them better