thmodel_ios_model/model/Classes/Controllers/MineVC/SwitchClientPresentationController.m

//
//  SwitchClientPresentationController.m
//  model
//
//  Created by Drew on 2018/12/14.
//  Copyright © 2018 Mine. All rights reserved.
//

#import "SwitchClientPresentationController.h"

@implementation SwitchClientPresentationController
- (instancetype)initWithPresentedViewController:(UIViewController *)presentedViewController presentingViewController:(UIViewController *)presentingViewController {
    self = [super initWithPresentedViewController:presentedViewController presentingViewController:presentingViewController];
    if (self) {
        // 必须设置 presentedViewController 的 modalPresentationStyle
        // 在自定义动画效果的情况下，苹果强烈建议设置为 UIModalPresentationCustom
        presentedViewController.modalPresentationStyle = UIModalPresentationCustom;
    }
    return self;
}
// 呈现过渡即将开始的时候被调用的
// 可以在此方法创建和设置自定义动画所需的view
- (void)presentationTransitionWillBegin {
    self.containerView.layer.cornerRadius = 14;
    // 背景遮罩
    UIView *dimmingView = [[UIView alloc] initWithFrame:self.containerView.bounds];
    dimmingView.backgroundColor = [UIColor blackColor];
    dimmingView.opaque = NO; //是否透明
    dimmingView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    [dimmingView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dimmingViewTapped:)]];
    self.dimmingView = dimmingView;
    
    [self.containerView addSubview:dimmingView]; // 添加到动画容器View中。
    
    // 获取presentingViewController 的转换协调器，应该动画期间的一个类？上下文？之类的，负责动画的一个东西
    id<UIViewControllerTransitionCoordinator> transitionCoordinator = self.presentingViewController.transitionCoordinator;
    
    // 动画期间，背景View的动画方式
    self.dimmingView.alpha = 0.f;
    [transitionCoordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {
        self.dimmingView.alpha = 0.4f;
    } completion:NULL];
}

#pragma mark 点击了背景遮罩view
- (void)dimmingViewTapped:(UITapGestureRecognizer*)sender {
    [self.presentingViewController dismissViewControllerAnimated:YES completion:NULL];
}

// 在呈现过渡结束时被调用的，并且该方法提供一个布尔变量来判断过渡效果是否完成
- (void)presentationTransitionDidEnd:(BOOL)completed {
    // 在取消动画的情况下，可能为NO，这种情况下，应该取消视图的引用，防止视图没有释放
    if (!completed) {
        self.dimmingView = nil;
    }
}

// 消失过渡即将开始的时候被调用的
- (void)dismissalTransitionWillBegin {
    id<UIViewControllerTransitionCoordinator> transitionCoordinator = self.presentingViewController.transitionCoordinator;
    
    [transitionCoordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {
        self.dimmingView.alpha = 0.f;
    } completion:NULL];
}

// 消失过渡完成之后调用，此时应该将视图移除，防止强引用
- (void)dismissalTransitionDidEnd:(BOOL)completed {
    if (completed == YES) {
        [self.dimmingView removeFromSuperview];
        self.dimmingView = nil;
    }
}

// 返回目标控制器Viewframe
- (CGRect)frameOfPresentedViewInContainerView {
    // 这里直接按照想要的大小写死，其实这样写不好，在第二个Demo里，我们将按照苹果官方Demo，写灵活的获取方式。
    CGFloat height = 260.f;
    CGFloat width = 300.f;
    CGRect containerViewBounds = CGRectMake((self.containerView.bounds.size.width - width) / 2, (self.containerView.bounds.size.height - height) / 2, width, height);
    return containerViewBounds;
}

//  建议就这样重写就行，这个应该是控制器内容大小变化时，就会调用这个方法， 比如适配横竖屏幕时，翻转屏幕时
//  可以使用UIContentContainer的方法来调整任何子视图控制器的大小或位置。
- (void)preferredContentSizeDidChangeForChildContentContainer:(id<UIContentContainer>)container {
    [super preferredContentSizeDidChangeForChildContentContainer:container];
    if (container == self.presentedViewController) [self.containerView setNeedsLayout];
}

- (void)containerViewWillLayoutSubviews {
    [super containerViewWillLayoutSubviews];
    self.dimmingView.frame = self.containerView.bounds;
}
@end