UINavigationController動畫變化

Question

我來自這個問題：How to change the Push and Pop animations in a navigation based app

我想扭轉推動和流行的動畫。所以，而不是默認動畫到右邊，它應該去左邊，反之亦然。

我創建了UINavigationController的一個子類，並重寫了push和pop方法。

下面是代碼：

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated 
{ 
    CATransition* transition = [CATransition animation]; 
    transition.duration = 0.4; 
    transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; 
    transition.type = kCATransitionPush;//kCATransitionFade; //kCATransitionMoveIn; //, kCATransitionPush, kCATransitionReveal, kCATransitionFade 
    transition.subtype = kCATransitionFromLeft; //kCATransitionFromLeft, kCATransitionFromRight, kCATransitionFromTop, kCATransitionFromBottom 
    [self.view.layer addAnimation:transition forKey:nil]; 

    [super pushViewController:viewController animated:NO]; 
} 

- (UIViewController *)popViewControllerAnimated:(BOOL)animated 
{ 
    CATransition* transition = [CATransition animation]; 
    transition.duration = 0.4; 
    transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; 
    transition.type = kCATransitionPush;//kCATransitionFade; //kCATransitionMoveIn; //, kCATransitionPush, kCATransitionReveal, kCATransitionFade 
    transition.subtype = kCATransitionFromRight; //kCATransitionFromLeft, kCATransitionFromRight, kCATransitionFromTop, kCATransitionFromBottom 
    [self.view.layer addAnimation:transition forKey:nil]; 

    UIViewController *poppedVC = [super popViewControllerAnimated:NO]; 

    return poppedVC; 
} 

到目前爲止，這些都完美的工作。

在這些方法中，行[self.view.layer addAnimation:transition forKey:nil];讓我感到困惑。我發現，在每次調用方法時，都會初始化一個新的CATransition對象並將其添加到視圖的圖層中。我不確定這對記憶有什麼影響。它是否安全？如果不是，我該怎麼做纔不會傷害記憶/表現？

Answer 1

一個簡單的解決方案就是每次添加一個CATransition ivar（或屬性）並重用它。也就是說，我懷疑這會顯着影響性能，在確定性能問題之前，擔心性能通常不會有用。

所以，總之不用擔心。如果您擔心這一點，請製作一種用於這些方法的單一伊娃。