iOS实现导航栏透明示例代码

PopAnimation.m

#import "PopAnimation.h"

@interface PopAnimation ()
@property (nonatomic, strong) id <UIViewControllerContextTransitioning> transitionContext;
@end

@implementation PopAnimation

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {
  //这个方法返回动画执行的时间
  return 0.25;
}

/**
 * transitionContext你可以看作是一个工具，用来获取一系列动画执行相关的对象，并且通知系统动画是否完成等功能。
 */
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext {
  /**
   * 获取动画来自的那个控制器
   */
  UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
  /**
   * 获取转场到的那个控制器
   */
  UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

  /**
   * 转场动画是两个控制器视图时间的动画，需要一个containerView来作为一个“舞台”，让动画执行。
   */
  UIView *containerView = [transitionContext containerView];
  [containerView insertSubview:toViewController.view belowSubview:fromViewController.view];

  NSTimeInterval duration = [self transitionDuration:transitionContext];

  /**
   * 执行动画，我们让fromVC的视图移动到屏幕最右侧
   */
  [UIView animateWithDuration:duration animations:^{
    fromViewController.view.transform = CGAffineTransformMakeTranslation([UIScreen mainScreen].bounds.size.width, 0);
  }completion:^(BOOL finished) {
    /**
     * 当你的动画执行完成，这个方法必须要调用，否则系统会认为你的其余任何操作都在动画执行过程中。
     */
    [transitionContext completeTransition:!transitionContext.transitionWasCancelled];
  }];

}

- (void)animationDidStop:(CATransition *)anim finished:(BOOL)flag {
  [_transitionContext completeTransition:!_transitionContext.transitionWasCancelled];
}
@end