CODEWITHSUNDEEP
iosswiftuiimagecgimage
Sunay
Sunay

Reputation: 417

Converting UIImage to CGImage to get Pixel Color

Based on code from this question (How do I get the color of a pixel in a UIImage with Swift?), I'm trying to run a function when a button gets tapped. Here is my code thus far:

@IBOutlet weak var graphImage: UIImageView!

var image : UIImage?

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

func getPixelColor(pos: CGPoint) -> UIColor {
    var pixelData = CGDataProviderCopyData(CGImageGetDataProvider(self.image!.CGImage))
    var data : UnsafePointer<UInt8> = CFDataGetBytePtr(pixelData)

    var pixelInfo : Int = ((Int(image!.size.width) * Int(pos.y) + Int(pos.x)*4))

    let r = CGFloat(data[pixelInfo])
    let g = CGFloat(data[pixelInfo]+1)
    let b = CGFloat(data[pixelInfo]+2)
    let a = CGFloat(data[pixelInfo]+3)

    return UIColor(red: r, green: g, blue: b, alpha: a)
}

@IBAction func playTapped(sender: AnyObject) {
    var c : CGFloat = 100.0
    var d : CGFloat = 100.0
    getPixelColor(CGPoint(x:c,y:d))
}

However, whenever I tap the play button in the iOS Simulator, the app crashes and I get the warning "fatal error: unexpectedly found nil while unwrapping an Optional value" on the first line of the function getPixelColor. What am I doing wrong here/what do I need to add?

Upvotes: 0

Views: 1349

Answers (1)

davecom
davecom

Reputation: 1498

Pretty straight forward. Based on the code here, you are indeed unwrapping a nil object. Your instance variable, image, is never initialized to anything... So you're trying to force unwrap it with ! but it is actually nil.

Upvotes: 1

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