自定义present和dismiss的转场动画

趁周末闲暇之余，重新写一下present和push的自定义动画。
本来之前有写过一个，因为没有及时整理，到导致一时凌乱，找不到具体在哪了，提醒各位，平时要注意代码的整理和归档，不然到时候重复的代码写了又写，那就得不偿失了。废话不过说，先看下下面的效果：

原生的present是从底部向上弹出相应的视图控制器，而push动画，则是将视图从右边推出来进行展示，为了视图展示的统一性，需要自定义转场动画，将present改成从右往左推出来展示，在dismiss的VC中需要增加一个左边的手势，以满足侧滑返回的效果。

首先需要主页VC实现UIViewControllerTransitioningDelegate这个代理中的2个方法

#pragma mark - UIViewControllerTransitioningDelegate
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source{
    return [[YQPresentTransitionAnimated alloc] init];
}

- (id <UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed {
    return [[YQDismissTransitionAnimated alloc] init];
}

将它的present动画和dismiss动画交给我们自定义的动画来管理。

present动画的自定义####

1.创建一个类，继承至NSObject,并实现UIViewControllerAnimatedTransitioning的代理;

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface YQPresentTransitionAnimated : NSObject<UIViewControllerAnimatedTransitioning>

@end

2.实现代理的2个方法

//1.定义转场动画的时间
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
    return 0.4;
}

//2.实现转场动画的动画效果
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
    UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];   //主页VC
    UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];     //present的VC
    
    UIView *containerView = transitionContext.containerView;  //转场的容器视图，动画完成后，会消失
    UIView *fromView;
    UIView *toView;

    if ([transitionContext respondsToSelector:@selector(viewForKey:)]) {
        fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];
        toView = [transitionContext viewForKey:UITransitionContextToViewKey];
    } else {
        fromView = fromViewController.view;
        toView = toViewController.view;
    }
    
    //注意这个对应关系
    BOOL isPresenting = (toViewController.presentingViewController == fromViewController);
    
    CGRect fromFrame = [transitionContext initialFrameForViewController:fromViewController];
    CGRect toFrame = [transitionContext finalFrameForViewController:toViewController];
    
    if (isPresenting) {
        fromView.frame = fromFrame;
        toView.frame = CGRectOffset(toFrame, toFrame.size.width, 0);
    }
    
    if (isPresenting)
        [containerView addSubview:toView];
    
    NSTimeInterval transitionDuration = [self transitionDuration:transitionContext];
    
    [UIView animateWithDuration:transitionDuration animations:^{
        if (isPresenting) {
            toView.frame = toFrame;
            fromView.frame = CGRectOffset(fromFrame, fromFrame.size.width * 0.3 * -1, 0);
        }
    } completion:^(BOOL finished) {
        //固定写法
        BOOL wasCancelled = [transitionContext transitionWasCancelled];
        
        if (wasCancelled)
            [toView removeFromSuperview];
        
        [transitionContext completeTransition:!wasCancelled];
    }];
}

3.将主页VC的transitioningDelegate设为自己，【千万注意】：还需要将present的页面的transitioningDelegate设为自己（主页VC）

dismiss动画的自定义####

跟上面的present步骤一样，只需将动画效果换成相反的即可。

附上源码：
https://github.com/GitterYang/YQPresentAnimation