如何删除 UIImageView

Question

我正在制作一个应用程序，用户可以在其中添加和删除不同类型的 UIImageview 对象以显示，例如头发鼻子等。我已经将图像添加到视图中，我面临的唯一问题是如何删除这些图像我正在使用 PanGestureRecognizer我想知道拖到顶部时删除 Imageview 见下图。

Answer 1

这里的删除是错误的词。

您可以将它从它的超级视图中删除，如果没有其他对象保持对它的强引用，这将破坏 imageView。

[imageView removeFromSuperView];

或者你可以让它显示 nil 而不是图像，这将确保你的 imageView 仍然在这里但它不显示任何东西。

imageView.image=nil;

如果你想从一个 NSMutableArray 的 extraFeatures 中删除显示的图像，你可以：

[self.extraFeatures removeObject:imageView.image];

然后

[imageView removeFromSuperView];

** 编辑：平移手势

- (void)pan:(UIPanGestureRecognizer *)sender
{
    // move begins
    if(sender.state == UIGestureRecognizerStateBegan)
    {
      // Do something when the move begin???
      // Maybe record the initial position
    }

    // Move the view around during the pan
    else if (sender.state == UIGestureRecognizerStateChanged)
    {
        CGPoint move = [sender translationInView:self.view];
        sender.view.center = CGPointMake(sender.view.center.x + move.x, sender.view.center.y + move.y);
        [sender setTranslation:CGPointZero inView:self.view];

         // test if we should remove the view, viewCenter outside of viewbounds
        if(!CGRectContainsPoint(self.view.bounds, imageView.center))
        {
            [sender.view removeFromSuperView];
        }
    }

    // End of move
    else if (sender.state == UIGestureRecognizerStateEnded)
    {

        // test if we should remove the view, viewCenter outside of viewbounds
        if(!CGRectContainsPoint(self.view.bounds, imageView.center))
        {
            [sender.view removeFromSuperView];
        }

        // else maybe comming back to the original position
    }
}

Answer 2

- (void)pan:(UIPanGestureRecognizer *)sender
{

typedef NS_ENUM(NSUInteger, UIPanGestureRecognizerDirection) {
    UIPanGestureRecognizerDirectionUndefined,
    UIPanGestureRecognizerDirectionUp,
    UIPanGestureRecognizerDirectionDown,
    UIPanGestureRecognizerDirectionLeft,
    UIPanGestureRecognizerDirectionRight
};

static UIPanGestureRecognizerDirection direction = UIPanGestureRecognizerDirectionUndefined;

switch (sender.state) {

    case UIGestureRecognizerStateBegan: {

        if (direction == UIPanGestureRecognizerDirectionUndefined) {

            CGPoint velocity = [sender velocityInView:recognizer.view];

            BOOL isVerticalGesture = fabs(velocity.y) > fabs(velocity.x);

            if (isVerticalGesture) {
                if (velocity.y > 0) {
                    direction = UIPanGestureRecognizerDirectionDown;
                } else {
                    direction = UIPanGestureRecognizerDirectionUp;
                }
            }

            else {
                if (velocity.x > 0) {
                    direction = UIPanGestureRecognizerDirectionRight;
                } else {
                    direction = UIPanGestureRecognizerDirectionLeft;
                }
            }
        }

        break;
    }

    case UIGestureRecognizerStateChanged: {
        switch (direction) {
            case UIPanGestureRecognizerDirectionUp: {
                [self handleUpwardsGesture:sender];
                break;
            }
            case UIPanGestureRecognizerDirectionDown: {
                [self handleDownwardsGesture:sender];
                break;
            }
            case UIPanGestureRecognizerDirectionLeft: {
                [self handleLeftGesture:sender];
                break;
            }
            case UIPanGestureRecognizerDirectionRight: {
                [self handleRightGesture:sender];
                break;
            }
            default: {
                break;
            }
        }
    }

    case UIGestureRecognizerStateEnded: {
        direction = UIPanGestureRecognizerDirectionUndefined;   
        break;
    }

    default:
        break;
}

}

- (void)handleUpwardsGesture:(UIPanGestureRecognizer *)sender
{
    NSLog(@"Up");
}

- (void)handleDownwardsGesture:(UIPanGestureRecognizer *)sender
{
    NSLog(@"Down");
}

- (void)handleLeftGesture:(UIPanGestureRecognizer *)sender
{
    NSLog(@"Left");
}

- (void)handleRightGesture:(UIPanGestureRecognizer *)sender
{
    NSLog(@"Right");
}

让我知道它是否适合你。

Answer 3

简单地做。

self.imageView.image = nil;