ios - How do I get subclass to initialize property as its correct class? -

i have class named sppanelmanager, has property of class, named sppanelsettingsmanager. sppanelmanager has following in it's -init method:

self.settingsmanager = [[sppanelsettingsmanager alloc] init]; 

the purpose of sppanelmanager subclassed, , subclasses used throughout app. example, there's spgreetingmanager. in .h file of spgreetingmanager, have declared:

@property (nonatomic, strong) spgreetingsettingsmanager *settingsmanager; 

which makes settingsmanager of correct class. problem when spgreetingmanager subclass initialized, calls init method above, , initializes settingsmanager sppanelsettingsmanager class, rather spgreetingsettingsmanager.

how can initialize correct class property without having re-write init code in every subclass?

the super class (sppanelmanager) somehow has know class concrete panel manager wants use settingsmanager.

apple uses following approach match calayers uiviews:

the base class declares class method returns concrete sppanelsettingsmanager subclass:

// in sppanelmanager.h + (class)settingsmanagerclass; 

... subclasses override return custom class:

// in spgreetingmanager.m + (class)settingsmanagerclass {     return [spgreetingsettingsmanager class]; } 

now superclass can instantiate settings manager follows:

self.settingsmanager = [[[[self class] settingsmanagerclass] alloc] init];