iOS-授之以鱼不如授之以渔=_=带你升入理解自定义转场动画

1.前言

说到APP的转场动画，大家一定会想到push和pop来实现转场动画，这是苹果用了很多年提供的自带的方法，而且我相信大家在APP开发的时候，很多小伙伴都会选择自带的转场动画，很少去自定义，不论你是大神还是小白菜，本小白菜也是一样，毕竟作为程序员的我们已经很累了，项目经理不提我们也很少回去做，但是我们工作不是为了工作而工作，是为了丰富充实自己。

2.自定义UINavigationController

当UINavigationController对UIViewController进行pop或者push的时候，我们需要让UIViewController知道我们进行这些操作，这里我们需要UINavigationController的代理UINavigationControllerDelegate，UINavigationControllerDelegate的代理方法有六种，这里我们只需要一张，那就是：

#pragma mark - UINavigationControllerDelegate
- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC;

代码如下：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    [self uiConfig];
}

- (void)uiConfig{
    self.delegate = self;
}

#pragma mark - UINavigationControllerDelegate
- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC{
    ZFJ_Animation *ZFJAnimation = [[ZFJ_Animation alloc]init];
    ZFJAnimation.operation = operation;
    ZFJAnimation.animationType = _animationType;
    return (id)ZFJAnimation;
}

3.自定义动画（ZFJ_Animation）

ZFJ_Animation这个类继承于NSObject，参数如下：

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

typedef NS_ENUM(NSInteger, ZFJ_AnimationType) {
    ZFJ_AnimationType1,
    ZFJ_AnimationType2,
    ZFJ_AnimationType3
};

@interface ZFJ_Animation : NSObject

@property (nonatomic,assign) UINavigationControllerOperation operation;

@property (nonatomic,assign) ZFJ_AnimationType animationType;//动画类型

@end

参数说明
operation用来接收控制器的转场类型，UINavigationControllerOperation是个枚举类型，类型如下：

typedef NS_ENUM(NSInteger, UINavigationControllerOperation) {
    UINavigationControllerOperationNone,
    UINavigationControllerOperationPush,
    UINavigationControllerOperationPop,
};

看到这个枚举大家就明白了，看你的UIViewController是push还是pop，这样我们可以根据这个类型来定义不同的类型；

animationType我自定义转场的动画类型，也是一个枚举，因为在ZFJ_Animation里面我打算定义几个不同的动画类型；

当然最重要的就是这个动画控制器的类必须遵循一个代理方法UIViewControllerAnimatedTransitioning，代理的里面的两个方法也必须要实现，代理方法如下：

@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.
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;
// This method can only  be a nop if the transition is interactive and not a percentDriven interactive transition.
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;

@optional

代理说明

a.transitionDuration：这个方法返回自定义动画的执行时间；

b.animateTransition：这个方法是我们这个动画管理类的核心，我们需要自定义什么样的动画全部在这里面执行；

上代码：

#pragma mark - UIViewControllerAnimatedTransitioning
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext{
    return 0.4;
}

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext{
    UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    
    UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    UIView *containerView = transitionContext.containerView;

    if(self.animationType == ZFJ_AnimationType1){
        //动画一
        [containerView addSubview:toViewController.view];
        
        CGRect fromViewStartFrame = [transitionContext initialFrameForViewController:fromViewController];
        CGRect toViewEndFrame = [transitionContext finalFrameForViewController:toViewController];
        CGRect fromViewEndFrame = fromViewStartFrame;
        CGRect toViewStartFrame = toViewEndFrame;
        
        if(self.operation == UINavigationControllerOperationPush){
            //PUSH
            toViewStartFrame.origin.y -= toViewEndFrame.size.height;
        }else if (self.operation == UINavigationControllerOperationPop){
            //POP
            fromViewEndFrame.origin.y -= fromViewStartFrame.size.height;
            [containerView sendSubviewToBack:toViewController.view];
        }
        //这里面 你可以自定义动画
        fromViewController.view.frame = fromViewStartFrame;
        toViewController.view.frame = toViewStartFrame;
        
        //动画
        CGFloat duration = [self transitionDuration:transitionContext];
        [UIView animateWithDuration:duration animations:^{
            fromViewController.view.frame = fromViewEndFrame;
            toViewController.view.frame = toViewEndFrame;
        } completion:^(BOOL finished) {
            [transitionContext completeTransition:YES];
        }];
    }else if(self.animationType == ZFJ_AnimationType2){
        //动画二
    }else if (self.animationType == ZFJ_AnimationType3){
        //动画三
    }
    
}

说明：这里面我定义了三种动画，因为页面展示太长，我就展示一种动画。

4.UIViewController调用

- (void)nextBtnClick:(UIButton *)nextBtn{
    NSInteger index = nextBtn.tag - 100;
    ZFJ_NavViewController *nvc = (ZFJ_NavViewController *)self.navigationController;
    nvc.animationType = (ZFJ_AnimationType)index;
    ZFJ_NextViewController *zvc = [[ZFJ_NextViewController alloc]init];
    [nvc pushViewController:zvc animated:YES];
}

5.效果展示

6.DEMO下载

点击下载

http://download.csdn.net/detail/u014220518/9883291

iOS-授之以鱼不如授之以渔=_=带你升入理解自定义转场动画

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