Question

ios 怎么获取系统push/pop转场动画的时间

Answer 1

视图切换种类
如下效果图，这是有两大类视图切换动画的，一种是交互式的，另一种就是自定义的。

本篇只讲其中的UIViewControllerAnimatedTransitioning协议，来实现push、pop动画效果。另外的几个，后面会继续学习总结!!!
协议
我们要实现push、pop自定义转场效果，我们必须要有一个遵守了UIViewControllerAnimatedTransitioning协议且实现其必须实现的代理方法的类。
我们先来学习UIViewControllerAnimatedTransitioning协议：
@protocol UIViewControllerAnimatedTransitioning <NSObject>

// This is used for percent driven interactive transitions, as well as for container controllers that have companion animations that might need to
// synchronize with the main animation.
//
// 指定转场动画时长，必须实现，否则会Crash。
// 这个方法是为百分比驱动的交互转场和有对比动画效果的容器类控制器而定制的。
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;

// This method can only be a nop if the transition is interactive and not a percentDriven interactive transition.
// 若非百分比驱动的交互过渡效果，这个方法只能为空
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;

@optional

// This is a convenience and if implemented will be invoked by the system when the transition context's completeTransition: method is invoked.
- (void)animationEnded:(BOOL) transitionCompleted;

@end1234567891011121314151617181920

我们要实现目标效果，就需要一个定义一个类遵守UIViewControllerAnimatedTransitioning协议并实现相应的代理方法。
遵守UIViewControllerAnimatedTransitioning协议
下面，我们来定义一个转场类，这个类必须要遵守UIViewControllerAnimatedTransitioning协议，如下：
//
// HYBControllerTransition.h
// PushPopMoveTransitionDemo
//
// Created by huangyibiao on 15/12/18.
// Copyright © 2015年 huangyibiao. All rights reserved.
//

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

typedef NS_ENUM(NSUInteger, HYBControllerTransitionType) {
kControllerTransitionPush = 1 << 1,
kControllerTransitionPop = 1 << 2
};

@interface HYBControllerTransition : NSObject <UIViewControllerAnimatedTransitioning>

+ (instancetype)transitionWithType:(HYBControllerTransitionType)transitionType
duration:(NSTimeInterval)duration;

@end12345678910111213141516171819202122

我们只需要公开一个工厂方法来生成对象即可，调用更简单些。第个参数用于指定是哪种类型，是push还是pop，第二个参数是用于指定动画时长。
实现文件
我们一步步分析下面的关键代码：
//
// HYBControllerTransition.m
// PushPopMoveTransitionDemo
//
// Created by huangyibiao on 15/12/18.
// Copyright © 2015年 huangyibiao. All rights reserved.
//

#import "HYBControllerTransition.h"
#import "ViewController.h"
#import "DetailController.h"

@interface HYBControllerTransition ()

@property (nonatomic, assign) HYBControllerTransitionType transitionType;
@property (nonatomic, assign) NSTimeInterval duration;

@end

@implementation HYBControllerTransition

- (instancetype)init {
if (self = [super init]) {
self.transitionType = kControllerTransitionPush;
}

return self;
}

+ (instancetype)transitionWithType:(HYBControllerTransitionType)transitionType
duration:(NSTimeInterval)duration {
HYBControllerTransition *transition = [[HYBControllerTransition alloc] init];
transition.transitionType = transitionType;
transition.duration = duration;

return transition;
}

#pragma mark - UIViewControllerAnimatedTransitioning
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
switch (self.transitionType) {
case kControllerTransitionPush: {
[self push:transitionContext];
break;
}
case kControllerTransitionPop: {
[self pop:transitionContext];
break;
}
default: {
break;
}
}
}

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
return self.duration;
}

- (void)animationEnded:(BOOL)transitionCompleted {
NSLog(@"%s", __FUNCTION__);
}

#pragma mark - Private
- (void)pop:(id<UIViewControllerContextTransitioning>)transitionContext {
DetailController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
ViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *containerView = [transitionContext containerView];

UIView *toImageView = toVC.isImg1 ? toVC.img1 : toVC.img2;

UIView *tempView = containerView.subviews.lastObject;

// 第一个view是fromVC.view
// 第二个view是push进来时所生成的toImageView截图
for (UIView *view in containerView.subviews) {
NSLog(@"%@", view);
if (fromVC.view == view) {
NSLog(@"YES");
}
}

toImageView.hidden = YES;
tempView.hidden = NO;
// 必须保证将toVC.view放在最上面，也就是第一个位置
[containerView insertSubview:toVC.view atIndex:0];

[UIView animateWithDuration:self.duration
delay:0.0
usingSpringWithDamping:0.55
initialSpringVelocity:1/ 0.55
options:0
animations:^{
fromVC.view.alpha = 0.0;
tempView.frame = [toImageView convertRect:toImageView.bounds toView:containerView];
} completion:^(BOOL finished) {
tempView.hidden = NO;
toImageView.hidden = NO;
[tempView removeFromSuperview];

[transitionContext completeTransition:YES];

for (UIView *view in containerView.subviews) {
NSLog(@"%@", view);
if (toVC.view == view) {
NSLog(@"YES");
}
}
}];
}

- (void)push:(id<UIViewControllerContextTransitioning>)transitionContext {
ViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
DetailController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *containerView = [transitionContext containerView];

UIView *fromImageView = fromVC.isImg1 ? fromVC.img1 : fromVC.img2;
UIView *tempView = [fromImageView snapshotViewAfterScreenUpdates:NO];
tempView.frame = [fromImageView convertRect:fromImageView.bounds toView:containerView];

UIView *toImageView = toVC.imgView;

fromImageView.hidden = YES;
toVC.view.alpha = 0.0;
toImageView.hidden = YES;

[containerView addSubview:toVC.view];
[containerView addSubview:tempView];

[UIView animateWithDuration:self.duration
delay:0.0
usingSpringWithDamping:0.55
initialSpringVelocity:1/ 0.55
options:0
animations:^{
toVC.view.alpha = 1.0;
tempView.frame = [toImageView convertRect:toImageView.bounds toView:containerView];
} completion:^(BOOL finished) {
tempView.hidden = YES;
toImageView.hidden = NO;

[transitionContext completeTransition:YES];
}];
}
@end