我的博客：iOS使用系统的导航栏，自定义滑动返回手势与转场动画<br />

//自定义滑动返回手势与动画

//自定义转场动画

- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC{
    if (operation == UINavigationControllerOperationPush) {//push动画
        if(self.presentTransition){
            Class transition = NSClassFromString(self.presentTransition);
            return [transition new];
        }
    }
    else if (operation == UINavigationControllerOperationPop) {//pop动画
        if(self.dismissTransition){
            Class transition = NSClassFromString(self.dismissTransition);
            return [transition new];
        }
    }
    return nil;
}