iOS – 在关闭和滚动手势之间切换

2023年4月25日 454次阅读

Line Messenger应用程序(日本的事实上的信使应用程序)中有一种行为,我试图模仿.

基本上,它们有一个模态视图控制器,里面有滚动视图.当滚动动作到达其内容的顶部时,视图控制器无缝切换到交互式解雇动画.此外,当手势将视图返回到屏幕顶部时,控制返回到滚动视图.

这是它的外观的GIF.

《iOS – 在关闭和滚动手势之间切换》

对于我的生活,我无法弄清楚他们是如何做到的.我尝试了几种不同的方法,但它们都失败了,而且我没有想法.谁能指出我正确的方向？

EDIT2

为了澄清,我想要模仿的行为不仅仅是向下拖动窗口.我能做到,没问题.

我想知道相同的滚动手势(不抬起手指)如何触发解雇转换,然后在将视图拖回原始位置后将控制权转移回滚动视图.

这是我无法弄清楚的部分.

结束EDIT2

EDIT1

这是我到目前为止所拥有的.我能够使用滚动视图委托方法添加处理常规解雇动画的目标选择器,但它仍然无法按预期工作.

我创建了一个UIViewController,其UIWebView作为属性.然后我把它放在UINavigationController中,它以模态方式呈现.

导航控制器使用动画/转换控制器进行常规交互式解雇(可以通过导航栏上的手势来完成).

从这里开始,一切正常,但无法从滚动视图触发解雇.

NavigationController.h

@interface NavigationController : UINavigationController <UIViewControllerTransitioningDelegate>

@property (nonatomic, strong) UIPanGestureRecognizer *gestureRecog;

- (void)handleGesture:(UIPanGestureRecognizer*)gestureRecognizer;

@end

NavigationController.m

#import "NavigationController.h"
#import "AnimationController.h"
#import "TransitionController.h"

@implementation NavigationController {
    AnimationController *_animator;
    TransitionController *_interactor;
}

- (instancetype)init {
    self = [super init];

    self.transitioningDelegate = self;

    _animator = [[AnimationController alloc] init];
    _interactor = [[TransitionController alloc] init];

    return self;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    // Set the gesture recognizer
    self.gestureRecog = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handleGesture:)];
    [self.view addGestureRecognizer:_gestureRecog];
}

- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator {
    if (animator == _animator && _interactor.hasStarted) {
        return _interactor;
    }
    return nil;
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed {
    if (dismissed == self || [self.viewControllers indexOfObject:dismissed] != NSNotFound) {
        return _animator;
    }
    return nil;
}

- (void)handleGesture:(UIPanGestureRecognizer *)gestureRecog {
    CGFloat threshold = 0.3f;

    CGPoint translation = [gestureRecog translationInView:self.view];
    CGFloat verticalMovement = translation.y / self.view.bounds.size.height;
    CGFloat downwardMovement = fmaxf(verticalMovement, 0.0f);
    CGFloat downwardMovementPercent = fminf(downwardMovement, 1.0f);

    switch (gestureRecog.state) {
        case UIGestureRecognizerStateBegan: {
            _interactor.hasStarted = YES;
            [self dismissViewControllerAnimated:YES completion:nil];
            break;
        }
        case UIGestureRecognizerStateChanged: {
            if (!_interactor.hasStarted) {
                _interactor.hasStarted = YES;
                [self dismissViewControllerAnimated:YES completion:nil];
            }
            _interactor.shouldFinish = downwardMovementPercent > threshold;
            [_interactor updateInteractiveTransition:downwardMovementPercent];
            break;
        }
        case UIGestureRecognizerStateCancelled: {
            _interactor.hasStarted = NO;
            [_interactor cancelInteractiveTransition];
            break;
        }
        case UIGestureRecognizerStateEnded: {
            _interactor.hasStarted = NO;
            if (_interactor.shouldFinish) {
                [_interactor finishInteractiveTransition];
            } else {
                [_interactor cancelInteractiveTransition];
            }
            break;
        }
        default: {
            break;
        }
    }
}

@end

现在,我必须在滚动视图到达顶部时触发手势处理.所以,这就是我在视图控制器中所做的.

WebViewController.m

#import "WebViewController.h"
#import "NavigationController.h"

@interface WebViewController ()

@property (weak, nonatomic) IBOutlet UIWebView *webView;
@end

@implementation WebViewController {
    BOOL _isHandlingPan;
    CGPoint _topContentOffset;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    [self.webView.scrollView setDelegate:self];
}    

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    if ((scrollView.panGestureRecognizer.state == UIGestureRecognizerStateBegan ||
         scrollView.panGestureRecognizer.state == UIGestureRecognizerStateChanged) &&
        ! _isHandlingPan &&
        scrollView.contentOffset.y < self.navigationController.navigationBar.translucent ? -64.0f : 0) {

        NSLog(@"Adding scroll target");

        _topContentOffset = CGPointMake(scrollView.contentOffset.x, self.navigationController.navigationBar.translucent ? -64.0f : 0);
        _isHandlingPan = YES;
        [scrollView.panGestureRecognizer addTarget:self action:@selector(handleGesture:)];
    }
}
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    NSLog(@"Did End Dragging");
    if (_isHandlingPan) {
        NSLog(@"Removing action");
        _isHandlingPan = NO;
        [scrollView.panGestureRecognizer removeTarget:self action:@selector(handleGesture:)];
    }
}
- (void)handleGesture:(UIPanGestureRecognizer*)gestureRecognizer {
    [(NavigationController*)self.navigationController handleGesture:gestureRecognizer];
}

这仍然无法正常工作.即使在解雇动画期间,滚动视图仍然会以手势滚动.

结束EDIT1

最佳答案 这是一个自定义的交互式过渡.

首先,您需要设置UIViewController的transitioningDelegate

id<UIViewControllerTransitioningDelegate> transitioningDelegate;

然后将这两种方法实现

 //Asks your delegate for the transition animator object to use when dismissing a view controller.
 - animationControllerForDismissedController:
 //Asks your delegate for the interactive animator object to use when dismissing a view controller.
 - interactionControllerForDismissal:

当拖动到顶部时,您开始转换,您可以使用UIPercentDrivenInteractiveTransition来控制滚动期间的进度.

您也可以参考ZFDragableModalTransition的源代码

ZFDragableModalTransition的图片

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