Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value while applying effects to image

Question

I am trying to apply slide, fade and grow effect to my imageview. Following is my code

@IBAction func fadeIn(_ sender: Any) {
    imageView.alpha=0
    UIView.animate(withDuration: 1, animations: {
        self.imageView.alpha=1
    })
}

@IBAction func slideIn(_ sender: Any) {
    imageView.center=CGPoint(x:imageView.center.x-500,y:imageView.center.y)
    UIView.animate(withDuration: 2) {
        self.imageView.center=CGPoint(x:self.imageView.center.x+500,y:self.imageView.center.y)
    }

}

@IBAction func grow(_ sender: Any) {
    imageView.frame=CGRect(x:0,y:0,width:0,height:0)
    UIView.animate(withDuration: 1, animations: {
        self.imageView.frame=CGRect(x:0,y:0,width:200,height:200)
    })
}

Whenever i click on any of the button i get

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

Any help would be greatly appreciated.

Answer 1

(You have provided incomplete information in your question, so can't say exact root of issue. I can suggest this, according to information in question)

Your imageView should/may be an IBOutlet variable/property and you may not have connected it with your storyboard/XIB view controller interface element.

Solution:
Connect (or reconnect) your imageView with your interface element.

Answer 2

Hope all functions are correct for animation. You should first get unwrapped value then try to do further operation. It will result to avoid crash

IBAction func fadeIn(_ sender: Any) {
        if let img = imageView {
            img.alpha=0
            UIView.animate(withDuration: 1, animations: {
                self.img.alpha=1
            })
        }
    }

    @IBAction func slideIn(_ sender: Any) {
        if let img = imageView {
            img.center=CGPoint(x:img.center.x-500,y:img.center.y)
            UIView.animate(withDuration: 2) {
                self.img.center=CGPoint(x:self.img.center.x+500,y:self.img.center.y)
            }
        }

    }

    @IBAction func grow(_ sender: Any) {
        if let img = imageView {
            img.frame=CGRect(x:0,y:0,width:0,height:0)
            UIView.animate(withDuration: 1, animations: {
                self.img.frame=CGRect(x:0,y:0,width:200,height:200)
            })
        }
    }