Scope of an instance Variable in Objective C

Question

The question might sound pretty naive, ut this is really troubling me. I am trying to set an instance variable by calling an instance method method of a ViewController from another view controller. Basically here are the steps

I am in ViewController1
Initialized an object of ViewController2
Called an instance variable to set some values to the instance variable of ViewController2
Then finally called the presentModalViewController to load the view controller
Using the variables in viewWillAppear method, But the app crashes and on debugging it shows BAD_EXEC

I have tried printing the same in instance method and it prints there but crashing when trying to use somewhere outside the method.

I have also defined the property and also ynthesized the variable.

The only problem I can figure out is I am initializing the variable in methos ...Does that limit the scope of the variable.

Any kind of help would be highly appreciated.

Thanks in advance!!

cobbal · Accepted Answer · 2011-04-23 18:41:13Z

1

Most likely you're running into a memory management error, and without code all I can advise is to make sure you are familiar with Cocoa's memory management system:

http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/MemoryMgmt/MemoryMgmt.html

answered Apr 23, 2011 at 18:41

cobbal

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devsri Over a year ago

thanks a lot i read the doc and got the mistake i was making it was not retaining the object when initialized in an instance method

Ashwin · Accepted Answer · 2011-04-23 18:47:57Z

1

If you are creating the properties for the instance variable and synthesizing the getters and setters, you should be able to set the instance variable using dot notation:

viewController2.variable = foo;

or by using the setter method:

[viewController2 setVariable:foo];

You should not be trying to access the instance variables directly. By default, the scope is set to Protected, meaning that you can only access it by methods in the class, it's subclasses, and in category extensions.

answered Apr 23, 2011 at 18:47

Ashwin

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