ios - Need help on my tiny objective-c class design. How can I access my instance var? -

i playing around tiny app should store notes. ui uses master/detail view template.

my masterview holds instance of notecontroller in turn holds notes stored in array. save array using nskeyarchiver. know there method applicationdidenterbackground implemented in appdelegate.m.

but can't call instance method of notecontroller appdelegate. creating new instance wouldn't work neither data lost. what's wrong design?

i hope it's clear problem is. appreciated.

note.m:

@interface note : nsobject  @property (nonatomic, copy) nsstring *title; @property (nonatomic, copy) nsstring *content; @property (nonatomic, strong) nsdate *creationdate;  @end 

notecontroller.m:

@class note; @interface notedatacontroller : nsobject  @property (nonatomic, retain) nsmutablearray *masternotelist; @property (nonatomic, copy) nsstring *datafilepath;   - (nsuinteger) countoflist; - (note*) objectinlistatindex:(nsuinteger)theindex; - (void) addnote:(note*)thenote; - (void) removenote:(nsuinteger)theindex; - (void) loadmasterlist; - (void) savemasterlist;  @end 

my recommendation save note possible. if when -addnote: note realized (has title, content, etc.), preserve , there in adding. well, when -removenote:, save "notes file".

this simplifies matters, encapsulates management of notes notecontroller, , avoids having things somehow jack appdelegate.

however, if approach not work you, if need save when app enters background, have notecontroller observe uiapplicationdidenterbackgroundnotification , notecontroller have handler that end saves. mindful tho saving upon entering background may not ideal: if app exits before happens (e.g. crashes)? also, switching background isn't time engage in lengthy tasks, note preservation may not best suited time.