objective c - Objects being reset to NULL after being set to a non-NULL value -

i have 2 objective-c classes communicate data each other passing variables through method parameters. example might call method pass variable:

classx *x = [[classx alloc] init]; [x passthisparameter:i]; 

the variable received classx inside of passthisparameter method. can confirm breakpoints , log output:

- (void)passthisparameter:(id)object {     self.classvariable = object;     nslog(@"object: %@", self.classvariable); // in log can see classvariable has same value object does. } 

however when try use classvariable outside of above scope (ex. in method, in same class) shows null. why classvariable getting reset null? here how retrieveing variable later:

- (void)anothermethodfromclassx {     nslog(@"class variable: %@", self.classvariable); // null though variable never used anywhere else (except when it's set in method above) } 

i've tried setup variable in variety of ways in class definition / header , in implementation:

• @property (retain) id classvariable
• @property (strong) id classvariable
• @property (assign) id classvariable
• @property (nonatomic, strong) id classvariable

any ideas on why classvariable gets reset null? can't figure out , couldn't find on google. please forgive me if of programming terms incorrect.

edit: using arc, not mrc.

edit: possible classx reallocated , reinitialized after set classvariable reset null? reloaded in ui...

edit: here's classx , classz relevant code available online.

all of @property variants instance variables, value you're setting set onto instance, not class. so, when nothing retain x , gets destroyed arc value goes it. next time create new instance of classx it's clean , fresh value nil. solution retain x , reuse instead of allowing destroyed (and little research class , instance variables).