iOS 视图控制器转场动画/页面切换效果/跳转动画 学习

一 学习 在 UINavigationController 中 push 和 pop 的转场效果 

    (基于iOS7 以上的转场方式)

• 经过学习了解到,重点分三块:
• (1)pushAnimation: TransitionPushAnimation 进场效果动画管理器 (NSObject并遵守UIViewControllerAnimatedTransitioning协议)
• (2)popAnimation:   TransitionPopAnimation  出场效果动画管理器 (NSObject并遵守UIViewControllerAnimatedTransitioning协议) 
• (3)navigationPerformerObject: TransitionNavigationPerformer 对象操控转场 (设置转场动画代理遵从 UINavigationControllerDelegate协议)

    

用同一逻辑写了两个效果 来看, 转场代理方法实现差别不大. 关键 是 进出场效果,有人说”你的想象无限 动画效果无限”. 所以掌握了转场动画基本实现基本技巧后,就应该尝试深入研究一下动画效果的实现.这里强调实现转场动画原理和实现过程

   1 进场效果 和 出场效果 主要实现 UIViewControllerAnimatedTransitioning 协议的两个方法:

        (1)动画切换的持续时间,以秒为单位

        

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext

        (2)动画执行内容

    

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext

     注意要点: 判断 动画执行完成结果状态

      当用户做手指跟随操作的过程中,根据操作的finished位置 要判断此时应该是该结束动画 还是取消动画.

     [transitionContext completeTransition:![transitionContext transitionWasCancelled]];

      下面手势 就是 判断用户手势跟随进度  :

　　if ( progress > 0.5) {// 时为 完成 触发"返回"操作

             [self.interactionController finishInteractiveTransition];//transitionContext.transitionWasCancelled 会得到NO的回调
      } else {// 反之 为取消 保留当前页面

             [self.interactionController cancelInteractiveTransition];//transitionContext.transitionWasCancelled 会得到YES的回调

      }

      起初因为 [transitionContext transitionWasCancelled] 状态没注意导致 页面过渡 就那么卡住了 或者 页面空白,种种动画效果滞涩的问题都是 状态信号控制不好导致的

   2 这里需要遵从UINavigationControllerDelegate协议的两个方法,这两个方法在对屏幕进行翻转的时候对导航栏控制器变化的动画设置 :

    

- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                          interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);

- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                   animationControllerForOperation:(UINavigationControllerOperation)operation
                                                fromViewController:(UIViewController *)fromVC
                                                  toViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);

    通常写法是把导航去设置和代理方法写在对应的视图控制器里面,这里我们创建 一个对象TransitionNavigationPerformer 遵循UINavigationControllerDelegate代理方法,这样封装,耦合性低,并且代码可移植性更强.

 

    

#import <Foundation/Foundation.h>
@class TransitionPushAnimation;
@class TransitionPopAnimation;

@interface TransitionNavigationPerformer : NSObject <UINavigationControllerDelegate>

- (instancetype)initWithNav:(id)nav; //为了操控 self.navigationController

@property (weak, nonatomic)  UINavigationController *navigationController; //这里强调单项弱引用 

@property (strong, nonatomic) TransitionPushAnimation *pushAnimation;

@property (strong, nonatomic) TransitionPopAnimation *popAnimation;

@property (strong, nonatomic) UIPercentDrivenInteractiveTransition *interactionController;//没做特殊处理 就是默认系统创建 用来控制动画效果进度状态

@end

//
//  TransitionNavigationPerformer.m
//  SectionDemo
//
//  Created by HF on 17/3/29.
//  Copyright © 2017年 HF-Liqun. All rights reserved.
//

#import "TransitionNavigationPerformer.h"
#import "TransitionPopAnimation.h"
#import "TransitionPushAnimation.h"

@interface TransitionNavigationPerformer ()
{
    UIScreenEdgePanGestureRecognizer *panGesture;
}

@end

@implementation TransitionNavigationPerformer

- (instancetype)initWithNav:(id)nav
{
    self = [super init];
    if (self) {
        
        self.navigationController = nav;
        // 在导航控制器的视图上添加pan手势 --> 需要从边缘进行拖动，在控制器转换的时候是有用 "UIScreenEdgePanGestureRecognizer"
        panGesture = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
        panGesture.edges = UIRectEdgeLeft; //主要用作返回 left
        [self.navigationController.view addGestureRecognizer:panGesture];
        
        // 初始化动画方案
        self.pushAnimation = [[TransitionPushAnimation alloc] init];
        self.popAnimation  = [[TransitionPopAnimation alloc] init];
    }
    return self;
}

- (void)dealloc
{   //这里目的防止取消切换效果后 导航控制器仍然会对手势持有
    [panGesture removeTarget:self action:@selector(pan:)];
    self.interactionController = nil;
}

- (void)pan:(UIScreenEdgePanGestureRecognizer *)recognizer
{
    UIView *view = self.navigationController.view;
    CGFloat progress = [recognizer translationInView:view].x / (view.bounds.size.width * 1.0);
    progress = MIN(1.0, MAX(0.0, progress));
    
    if (recognizer.state == UIGestureRecognizerStateBegan) {
        // 创建过渡对象，弹出viewController
        self.interactionController = [[UIPercentDrivenInteractiveTransition alloc] init];
        [self.navigationController popViewControllerAnimated:YES];
    }
    else if (recognizer.state == UIGestureRecognizerStateChanged) {
        // 更新 interactive transition 的进度
        [self.interactionController updateInteractiveTransition:progress];
    }
    else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) {
        // 完成或者取消过渡
        if (progress > 0.5) { 
            [self.interactionController finishInteractiveTransition];
        }
        else {
            [self.interactionController cancelInteractiveTransition];
        }
        self.interactionController = nil;
    }
}

#pragma mark - UINavigationControllerDelegate

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                  animationControllerForOperation:(UINavigationControllerOperation)operation
                                               fromViewController:(UIViewController *)fromVC
                                                 toViewController:(UIViewController *)toVC
{
    if (operation == UINavigationControllerOperationPush) {
        return self.pushAnimation;
    }
    else if (operation == UINavigationControllerOperationPop) {
        return self.popAnimation;
    }
    return nil;
}

- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                         interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController {
    // 检查是否是我们的自定义过渡
    if ([animationController isKindOfClass:[TransitionPushAnimation class]] || [animationController isKindOfClass:[TransitionPopAnimation class]]) {
        return self.interactionController;
    }
    else {
        return nil;
    }
}

@end

     3 方法调用

     (1)在使用的时候 要添加self.navigationController.delegate = TransitionNavigationPerformer 对象, 不需要就设置为nil

     (2)页面viewWillDisappear 一定要立即取消代理方法 防止交互崩溃 .

    参考Demo:SectionDemo

     效果:

　　

参考:

http://www.open-open.com/lib/view/open1408677710366.html

http://www.cocoachina.com/ios/20150811/12986.html

https://github.com/seedante/iOS-Note/wiki/ViewController-Transition