objective c - Crashing iOS App with [Class retain]: message sent to deallocated instance -

i building app , i'm quite noob, please forgive lack of information!

i'm able crash app in set of steps reproduce, sometimes. when crashes, on main.m file with:

i've set exception breakpoint "throw" , separately "catch" , doesn't pick particular line of code on crash occurs.

how find out causing issue, or line(s) of code?

i testing on iphone 5s , 6 plus , crashes on both.

update

i have been doing testing , workflow of app.

i have uitableviewcontroller (called more tab). click on uiviewcontroller (called themes) , there's button there. click on button , calls uialertview. click on non-cancel button , calls uiviewcontroller (called iap). there's uibutton price , uibarbuttonitem called cancel. if click cancel, dismisses iap uiviewcontroller , goes themes uiviewcontroller.

the uibutton on iapviewcontroller dynamically calls price uiviewcontroller called unlimited entries.

i'm noticing crash if click on cancel button before price has loaded on uibutton.

with zombies, crash console shows:

2015-04-29 10:21:33.775 -[unliimitedentriespurchase retain]: message sent deallocated instance 0x174e4f4b0 

in viewdidload of iapviewcontroller, have:

[self.unlimitedentriespurchase validateproductidentifiers]; 

i have property created: @property (nonatomic, strong) unliimitedentriespurchase *unlimitedentriespurchase; , i'm thinking issue.

i hope makes sense , helps determine issue be.

it's rare case user come iap , click cancel button (to dismiss iapviewcontroller) before price loads on uibutton. however, it's i'd fix rather ship obvious issue.

update 2

in iapviewcontroller, have custom setter:

- (unliimitedentriespurchase *)unlimitedentriespurchase {     if (!_unlimitedentriespurchase)     {         _unlimitedentriespurchase = [[unliimitedentriespurchase alloc] init];         _unlimitedentriespurchase.delegate = self;     }     return _unlimitedentriespurchase; } 

with setting alloc , init in appdelegate, if statement not getting true here , custom delegate never gets set.

the probable cause firing action deallocated object, have that:

product ---> profile ---> zombies (in instruments)

and check in instrument tool object crashing.

you can reallocate object in place, example show how reallocate in appdelegate, first have add in appdelegate.h

@property (nonatomic, strong) unliimitedentriespurchase *unlimitedentriespurchase; + (appdelegate*) shareddelegate; 

and in appdelegate.m

+ (appdelegate*) shareddelegate {    return (appdelegate*)[uiapplication sharedapplication].delegate; } 

the in view controller have import appdelegate.h , allocate object that

[appdelegate shareddelegate].unlimitedentriespurchase = self.unlimitedentriespurchase; 

after can fire unlimitedentriespurchase methods becouse never going deallocated, if have problem can fire [appdelegate shareddelegate].unlimitedentriespurchase