IOS/Objective-C：导航栏自定义Segue效果对比Show Segue

Question

我有两个视图控制器，我使用常规的 Show Segue（从右到左）向一个方向移动，使用自定义的 Segue（从左到右）向另一个方向移动。我认为我不应该放松，因为两个 VC 都不从属于其他 VC，并且使用这些 segues 意味着一个导航控制器可以管理事情。

在两个 VC 的左上角，我有一个包含个人资料照片的公共 BarButton。

使用常规的从右到左 Segue 时，栏按钮上的个人资料照片保持不变。当屏幕的其余部分移入时，这看起来很棒，但两者共有的元素，个人资料照片保持在原位。

但是，在另一个方向（从左到右），使用自定义 segue，包括导航栏在内的整个 VC 屏幕突然进入，您基本上会看到个人资料照片从左边缘进入，然后停留在正常的左栏中同一张照片之前的按钮位置。这看起来很糟糕。

有没有办法强制导航栏中的公共元素在自定义转场期间保持原位，以更好地模仿系统显示转场的行为？

提前感谢您的任何建议。

这是我的自定义转场代码：

#import "customSegue.h"
#import "QuartzCore/QuartzCore.h"

@implementation customSegue

-(void)perform {

    UIViewController *destinationController = (UIViewController*)[self destinationViewController];

    UIViewController *sourceViewController = (UIViewController*)[self sourceViewController];
    CGFloat animationDuration = .40;  
    transition.duration = animationDuration;
    transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
    transition.type = kCATransitionMoveIn;  
    transition.subtype = kCATransitionFromLeft;  

    [sourceViewController.navigationController.view.layer addAnimation:transition
                                                                forKey:kCATransition];

    UIColor *previousWindowBackgroundColor = sourceViewController.view.window.backgroundColor;

    sourceViewController.view.window.backgroundColor = destinationController.view.backgroundColor;


    [sourceViewController.navigationController pushViewController:destinationController animated:NO];
    // switch the window color back after the transition duration from above
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(animationDuration * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        // make sure we still have a handle on the destination controller
        if (destinationController) {
            destinationController.view.window.backgroundColor = previousWindowBackgroundColor;
        }
    });

}

@end

Answer 1

你好@user6631314

我认为你不会通过使用 CATransition 并将其附加到 navigationController 视图的层来获得你想要的。

相反，我建议将 presentingViewController 设置为 UINavigationController 的委托，并为 LTR 推送滚动您自己的逻辑（导航栏会更加流畅，您不必再担心过渡期间的黑条我之前的回复帮助您解决/解决方法）。

为此，您需要将呈现视图控制器（或一些协调器视图控制器）设置为 UINavigationControllerDelegate 并实现此方法：

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                  animationControllerForOperation:(UINavigationControllerOperation)operation
                                               fromViewController:(UIViewController*)fromVC
                                                 toViewController:(UIViewController*)toVC

在该方法中，您需要检查操作是否为 UINavigationControllerOperationPush，如果是，则返回符合 UIViewControllerAnimatedTransitioning 协议的 NSObject 子类（否则返回 nil 以允许所有其他导航操作成为标准） .在该类中，您将处理自定义导航控制器推送动画覆盖。

LTR 推送动画的基本逻辑是，您要在屏幕左侧启动 toView，然后对其进行动画处理，使其在动画持续时间（代码中的 0.4）后完全显示在屏幕上——因此启动x 位置偏移到视图宽度的负值（因此它完全在屏幕外），然后在动画期间将 x 位置设置为 0（或者您可以只是 += 视图的宽度）。

这是当前自定义 segue 实现的示例（请注意导航栏也会滑过，这是您在此处发布的问题）：

以及使用自定义动画控制器的过渡：

完整代码如下：

#import "ViewController.h"
#import "LTRPushAnimator.h"

@interface ViewController () < UINavigationControllerDelegate>
@property (strong, nullable) UIView *profileView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationController.delegate = self;
    self.navigationItem.hidesBackButton = YES;
    self.profileView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
    UIImageView *profileImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Homer.jpg"]];
    [profileImageView setFrame:CGRectMake(0, 0, 40, 40)];
    profileImageView.layer.cornerRadius = 20.0f;
    profileImageView.layer.masksToBounds = YES;
    profileImageView.clipsToBounds = YES;
    profileImageView.layer.borderColor = [UIColor blackColor].CGColor;
    profileImageView.layer.borderWidth = 1.0f;
    [self.profileView addSubview:profileImageView];
    UIBarButtonItem *lbi = [[UIBarButtonItem alloc] initWithCustomView:self.profileView];
    self.navigationItem.leftBarButtonItem = lbi;
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
}

- (IBAction)pushFakeViewController:(id)sender {
    UIViewController *fakeViewController = [[UIViewController alloc] init];
    fakeViewController.view.backgroundColor = [UIColor redColor];
    UIBarButtonItem *lbi = [[UIBarButtonItem alloc] initWithCustomView:self.profileView];
    fakeViewController.navigationItem.leftBarButtonItem = lbi;
    fakeViewController.navigationItem.hidesBackButton = YES;
    [self.navigationController pushViewController:fakeViewController animated:YES];
    // this is just in here to pop back to the root view controller since we removed the back button, it can be removed obviously
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0f * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [self.navigationController popViewControllerAnimated:YES];
    });
}

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                  animationControllerForOperation:(UINavigationControllerOperation)operation
                                               fromViewController:(UIViewController*)fromVC
                                                 toViewController:(UIViewController*)toVC
{
    if (operation == UINavigationControllerOperationPush) {
        return [[LTRPushAnimator alloc] init];
    }
    // otherwise standard animation
    return nil;
}

@end

LTRPushAnimator.h

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

NS_ASSUME_NONNULL_BEGIN

@interface LTRPushAnimator : NSObject <UIViewControllerAnimatedTransitioning>

@end

NS_ASSUME_NONNULL_END

LTRPushAnimator.m

#import "LTRPushAnimator.h"

@implementation LTRPushAnimator

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext
{
    return 0.4;
}

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    [self _animatePushByFrameWithContext:transitionContext];
}

- (void)_animatePushByFrameWithContext:(id<UIViewControllerContextTransitioning>)transitionContext {
    UIViewController *toViewController   = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    CGRect toVCFrame = toViewController.view.frame;
    CGFloat viewWidth = toVCFrame.size.width;
    toVCFrame.origin.x -= viewWidth;
    [toViewController.view setFrame:toVCFrame];
    [[transitionContext containerView] addSubview:toViewController.view];
    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        CGRect finalVCFrame = toViewController.view.frame;
        finalVCFrame.origin.x = 0;
        [toViewController.view setFrame:finalVCFrame];
    } completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
    }];
}

@end