How to change specified image size in UIImageView with UISlider in Swift programmatically

Question

I'm trying to use the UISlider to change specified image size in UIImageView . The value range of the slider is 0 ~ 100. So the idea is that if I move the slider smaller, a specified image shows smaller, and If I move the slider bigger, the image size getting bigger.

This is the case when the image getting smaller: getting smaller image by UISlider

And this is the case when the image getting bigger: getting bigger image by UISlider

Can someone please help?

Answer 1

You will need to add Width and Aspect Ratio constraints to your image view -and obviously the other desired needed constraints-:

In my example, these are the constraints for the image view:

Next, you could implemnt the following:

class ViewController: UIViewController {

    @IBOutlet weak var slider: UISlider!
    @IBOutlet weak var imageViewWidth: NSLayoutConstraint!
    @IBOutlet weak var imageView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        slider.maximumValue = 100.0
        slider.value = 0.0
        imageViewWidth.constant = 20
    }

    @IBAction func sliderValueChanged(_ sender: Any) {
        imageViewWidth.constant = CGFloat(20 + slider.value)
    }
}

the imageViewWidth IBOutlet will be the width constraint of your image view that you want to resize.

Output:

Answer 2

Make the slider's value range from .01 to 1.0 (.01 should work better than 0.)

Control-drag from your slider into your view controller and create an action on the slider's valueChanged event. Let's call it sliderChanged .

In the slider's action method, change the scale on the image view:

@IBOutlet myImageView: UIImageView*


@IBAction func sliderChanged(sender: UISlider) {
  let scale = sender.value
  let transform = CGAffineTransform.scale(scaleX: scale, y: scale)
  myImageView.transform = transform
}

That should do it.

Answer 3

1. Update frames based on slider's value

2. Try multiplying UISlider's value with UIImageView's constraints