Instance pointers in an array

开发者_如何学编程I'm trying to save pointers of class instances into a mutable array. I'm able to do this but getting them back into use seems to be a problem. The next is how I inserted the pointers into the array:

Class *class = [Class new];
/* Do something with the instance */

[instanceArray addObject:class];

I am able to retrieve the wanted index from the array but when I try to access the instance variables etc. I only get compiler shouting at me or sometimes I get every variable as zero.

How am I supposed to get the instance back to use from the array? I know they are pointers but playing with them didn't seem to work.

Using addObject: the element is inserted at the end of the array. To retrieve it you can use -[NSArray objectAtIndex:]

Pointer arithmetic works in C since then your array is just a pointer to the first index, and array[i] is the same as *(array + i). In Objective-C this may still be done, however you're using an NSArray object. Now you don't have a pointer to the first object anymore, but to the instance of the class. To retrieve the objects stored in the array, you'll have to call the corresponding methods.

EDIT So you are able to retrieve it from the array and then your pointer is not nil, so you do have access to the object. You know in Objective-C, all instance variables are private so you can't access them from outside. You'd have to declare them as properties first (please refer to the documentation). Also, when you declare a variable to be of type id, accessing a property with dot-syntax doesn't work, it will cause a compiler error.