動畫隱藏或顯示導航條

[UIView beginAnimations:nil context:nil];[UIView setAnimationDelegate:self];[UIView setAnimationDidStopSelector:@selector(didAfterHidden)];[UIView setAnimationDuration:2.3];[view setAlpha:0.0f];[UIView commitAnimations];[UIView animateWithDuration:0.35                                      delay:0                                    options:(UIViewAnimationCurveEaseOut)                                 animations:^{                                     navigationBar_.alpha = 0.;                                 } completion:^(BOOL finished){                                     navigationBar_.hidden = YES;                                     navigationBar_.alpha = alpha;                                 }];

借UIView動畫，使更改導航條的hidden屬性這一過程動起來。