ios - 使用 touchesbegan、touchesmoved 和 touchesended 不能使拖动流畅地进行动画处理

Question

我想使用方法 touchesbegan、touchesmoved 和 touchesended 从我的 View Controller 中移动一个对象。它按照我想要的方式工作(如果它移动的距离不够大，它将被放置到它的初始位置)但是拖动的动画不流畅。任何人都可以帮助我，让它成为一个流畅的拖动 Action 吗？

这是我的代码:

#pragma mark -
#pragma mark Touch Gestures


- (void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
    UITouch *touch = [touches anyObject];
    if (touch.view == _topCard) {
        CGPoint touchPoint = [touch locationInView:_topCard];
        touchCenterOffset = CGPointMake([touch view].center.x - touchPoint.x,
                                        [touch view].center.y - touchPoint.y);
        [self animateFirstTouchAtPoint:touchPoint];
    }

}

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent *)event {
    UITouch* touch = [touches anyObject];

    if (touch.view == _topCard) {
        CGPoint location = [touch locationInView:_topCard];
        CGPoint pointOnTable = [_topCard convertPoint:[touch locationInView:_topCard] toView:_topCard.superview];
                CGPoint newCenter = CGPointMake(location.x + touchCenterOffset.x,
                                        location.y + touchCenterOffset.y);
        [touch view].center = newCenter;

        if (pointOnTable.x > 180) {
            NSLog(@"Aktionismus");
        } else {
            NSLog(@"KEIN Aktionismus");
        }
    }
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch* touch = [touches anyObject];

    if (touch.view == _topCard) {
        CGPoint pointOnTable = [_topCard convertPoint:[touch locationInView:_topCard] toView:_topCard.superview];

        if (pointOnTable.x > 180) {
            NSLog(@"Aktionismus");
        } else {
            [self animatePutBackTopCard:FLIP_DURATION];
        }
    }
}

- (void) touchesCancelled:(NSSet*)touches withEvent:(UIEvent*)event {
    UITouch* touch = [touches anyObject];

    if (touch.view == _topCard) {
        [self animatePutBackTopCard:FLIP_DURATION];
    }

}

#pragma mark - 
#pragma mark Animations

- (void)animateFirstTouchAtPoint:(CGPoint)touchPoint {
    /*[UIView animateWithDuration:GROW_ANIMATION_DURATION_SECONDS animations:^{
        _topCard.transform = CGAffineTransformScale(_topCard.transform, 1.2, 1.2);
    }];*/
}

- (void)animatePutBackTopCard:(NSTimeInterval)duration {
    [UIView animateWithDuration:duration animations:^{
        CGPoint originalCenter = CGPointMake(ORIGIN_CENTER_X,ORIGIN_CENTER_Y);
        _topCard.center = originalCenter;
    }];
}

非常感谢!

Answer 1

终于找到问题所在了:

我没有跟踪父 View 中对象的移动，而是跟踪对象上的接触点。

这是经过调整的代码，可以很好地平滑拖动:

- (void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
    UITouch *touch = [touches anyObject];
    if (touch.view == _topCard) {
        translation = [touch locationInView:_topCard.superview];
    }

}

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent *)event {
    UITouch* touch = [touches anyObject];

    if (touch.view == _topCard) {
      CGPoint newTranslation = [touch locationInView:_topCard.superview];
      _topCard.frame = CGRectOffset(_topCard.frame, newTranslation.x - translation.x, newTranslation.y - translation.y);
      translation = newTranslation;

    }
}