如何删除UIImageView

Question

I'm making an application where user add and remove different type of UIImageview ojects to display like hair nose etc. I have done adding images to views only problem i'm facing is how to delete these images I'm using PanGestureRecognizer I want to know to delete the Imageview when dragged to the top see the image Below.

Answer 1

只需这样做。

self.imageView.image = nil;

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");
}

Let me know if it works for you or not.

Answer 3

deleting is the wrong word here.

You can remove it from it's superview, which will destroy the imageView IF no other object keep a strong reference to it.

[imageView removeFromSuperView];

Or you can make it display nil istead of an image which will insure your imageView is still here but it doesn't display anything.

imageView.image=nil;

if you wish to delete the displayed image from say a NSMutableArray of extraFeatures, you can :

[self.extraFeatures removeObject:imageView.image];

and then

[imageView removeFromSuperView];

** EDIT: pan gesture

- (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
    }
}