objective-c - ブロック機能の目的はリテインサイクルですか？

Question

[UIView animateWithDuration:0.2
                          delay:0.0f
                        options:UIViewAnimationOptionCurveEaseIn
                     animations:^{
                         self.imgViewEnterFrame.alpha = 1.0 ;
                         self.imgViewOutofFrame.alpha = 0.0;
                         self.imgViewEnterFrame.frame = self.rectEnterGoodFrame;
                     }
                     completion:nil];