ios - What is the meaning of sending the "class" message to an instance of a class -

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in facebook login code @ https://developers.facebook.com/docs/facebook-login/ios/advanced, ask execute following sequence

  1. declare view displayed of "fbsdkloginbutton" class through storyboard.

  2. execute following line in app delegate didfinishlaunchingwithoptions.

    [fbsdkloginbutton class];

what meaning of sending "class" message object?

it used call initialize method of fbsdkloginbutton. +(void)initialize method called before instance of class initialised. called once. [fbsdkloginbutton class] used trigger initialize method called.


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