Show UIImageView for 1 second and hide again

Question

Hello. I am trying to show an image for a short time, in an animated way, and hidden again. This is the function:

@IBOutlet var statusField: UIImageView!
@IBAction func debugbutton(_ sender: UIButton) {
        showIcon()
}
override func viewDidLoad() {
        super.viewDidLoad()
        statusField.isHidden = true

func showIcon() {
        statusField.isHidden = false
        UIView.animate(withDuration: 1, delay: 0.5, options: UIView.AnimationOptions.transitionFlipFromTop, animations: {
            self.statusField.alpha = 0
        }, completion: { finished in
            self.statusField.isHidden = true
        })
    }

When I run the function for the first time it works fine but then it stops doing it. The icon is no longer displayed. Any advice on what's going on? Thanks!

2.0k

Posted by

sebasanblas

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Hello, just to clarify, you wanted to make the UIImageView flicker at 1 second interval, or just show it for 1 second and hide once?

—
rychee
Just show it for 1 second and hide once! Thanks!

—
sebasanblas

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Answer 1

In your animation, you set alpha to 0, but there's no code to reset it to 1.

    func showIcon() {
        statusField.isHidden = false
        UIView.animate(withDuration: 1, delay: 0.5, options: UIView.AnimationOptions.transitionFlipFromTop, animations: {
            self.statusField.alpha = 0
        }, completion: { finished in
            self.statusField.isHidden = true
            self.statusField.alpha = 1 //<-
        })
    }

In your shown code, showIcon() looks like it is nested inside viewDidLoad(), but it is odd and I assumed it is not nested.

Posted by

OOPer

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Answer 2

In your animation, you set alpha to 0, but there's no code to reset it to 1.

    func showIcon() {
        statusField.isHidden = false
        UIView.animate(withDuration: 1, delay: 0.5, options: UIView.AnimationOptions.transitionFlipFromTop, animations: {
            self.statusField.alpha = 0
        }, completion: { finished in
            self.statusField.isHidden = true
            self.statusField.alpha = 1 //<-
        })
    }

In your shown code, showIcon() looks like it is nested inside viewDidLoad(), but it is odd and I assumed it is not nested.

Posted by

OOPer

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Answer 3

It worked perfect, thank you very much. You are correct, the function was not nested, I just forgot to close viewDidLoad() when I was copying the code in the forum.

Besides knowing that it works, I would like to understand well how the code works. When I execute the function, the button appears (hidden = false) and then I have an animation that in a certain time (1s) varies the alpha from 1 to 0, upon completion it returns the value to 1 (thanks to you) and maintains I hide the image ( hidden = true ). It is right?

Posted by

sebasanblas

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Answer 4

When I execute the function, the button appears (hidden = false) and then I have an animation that in a certain time (1s) varies the alpha from 1 to 0, upon completion it returns the value to 1 (thanks to you) and maintains I hide the image ( hidden = true ). It is right?

Before you call, image is hidden and alpha is 1 (by default as defined in IB probably)

Before animation, you unhide : image is visible Then animation is to change progressively alpha from 1 to 0 ; hidden remains false At the end of animation, you hide the image again. and you need to reset alpha to 1, otherwise next time you play you start at 0

You could also have written it at start:

    func showIcon() {
        statusField.isHidden = false
        statusField.alpha = 1 //<-

Posted by

Claude31

Thanks for the explanation Claude!

—
sebasanblas

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Show UIImageView for 1 second and hide again

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