使用touchesbegan，touchesmoved和touchesended并不能平滑地拖动动画

Question

我想使用方法touchesbegan，touchesmoved和touchesended从我的viewcontroller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）但是拖动的动画并不平滑。谁能帮助我，让它成为一个流畅的拖动运动？

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

最后我想出了我的问题所在：

我没有跟踪超视图中对象的移动，而是跟踪对象上的接触点。

这是经过调整的代码，可以顺利拖动工作：

- (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;

    }
}

Answer 2

看看我是如何移动一个物体并且它正在顺利运行：

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

    CGPoint location = [touch locationInView:self.superview];
    float difx = [[touches anyObject] locationInView:self].x - [[touches anyObject] previousLocationInView:self].x;

    float dify = [[touches anyObject] locationInView:self].y - [[touches anyObject] previousLocationInView:self].y;

    CGAffineTransform newTransform1 = CGAffineTransformTranslate(self.transform, difx, dify);

    self.transform = newTransform1;
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint location = [touch locationInView:self.superview];
    float difx = [[touches anyObject] locationInView:self].x - [[touches anyObject] previousLocationInView:self].x;

    float dify = [[touches anyObject] locationInView:self].y - [[touches anyObject] previousLocationInView:self].y;

    CGAffineTransform newTransform1 = CGAffineTransformTranslate(self.transform, difx, dify);

    self.transform = newTransform1;

}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{

}

我认为你可以适应你的需求。

Answer 3

我使用以下代码拖动a custom UIView：

- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInView:self];
    CGPoint previous = [touch previousLocationInView:self];

    if (!CGAffineTransformIsIdentity(self.transform)) {
        location = CGPointApplyAffineTransform(location, self.transform);
        previous = CGPointApplyAffineTransform(previous, self.transform);
    }

    self.frame = CGRectOffset(self.frame,
                              (location.x - previous.x),
                              (location.y - previous.y));
}

Answer 4

如其他答案所述，直接操纵视图框架是不好的做法。例如，使用UIDynamics时会导致非常奇怪的行为。 你应该设置视图的中心。

  override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent) {
    if let touch = touches.first as? UITouch {

        let p1 = touch.locationInView(self.superview)
        let p0 = touch.previousLocationInView(self.superview)
        let translation = CGPointMake(p1.x - p0.x, p1.y - p0.y);
        center = CGPointMake(center.x + translation.x, center.y + translation.y)//set views center
    }
}

Answer 5

对于拖动，我建议改为使用panGestureRecognizer。

可以找到信息here