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iOS

Posted by Tessa Waldock
Tessa Waldock
30 Points

Store image in a var then press a button to remove one of the images in the array

I am creating a drawing app in Swift. In which every time a user draws a line on the UIImageVIew it rasterizes a new image. I would like to create an undo button which goes to the previous image in the array.

Here is my code -

func drawLineFrom(fromPoint: CGPoint, toPoint: CGPoint) {

// 1
UIGraphicsBeginImageContext(view.frame.size)

tempImageView.image?.draw(in: CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height))
let context = UIGraphicsGetCurrentContext()
// 2

context?.move(to: CGPoint(x: fromPoint.x, y: fromPoint.y))
context?.addLine(to: CGPoint(x: toPoint.x, y: toPoint.y))

// 3

context?.setBlendMode(CGBlendMode.normal)
context?.setLineCap(CGLineCap.round)
context?.setLineWidth(brushWidth)
context?.setStrokeColor(UIColor(red:red, green:green, blue:blue, alpha: 1.0).cgColor)

// 4
context?.strokePath()

// 5
tempImageView.image = UIGraphicsGetImageFromCurrentImageContext()
tempImageView.alpha = opacity
UIGraphicsEndImageContext()

}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) { swiped = true if let touch = touches.first { let currentPoint = touch.location(in: view) drawLineFrom(fromPoint: lastPoint, toPoint: currentPoint) lastPoint = currentPoint

}

}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) { if !swiped { // draw a single point drawLineFrom(fromPoint: lastPoint, toPoint: lastPoint)

}

// Merge tempImageView into mainImageView
UIGraphicsBeginImageContext(mainImageView.frame.size)
mainImageView.image?.draw(in: CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height),blendMode: CGBlendMode.normal, alpha: 1.0)
tempImageView.image?.draw(in: CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height), blendMode: CGBlendMode.normal, alpha: opacity)
mainImageView.image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
tempImageView.image = nil
floaty.isHidden = false
postBtn.isHidden = false
resetBtn.isHidden = false
undoBtn.isHidden = false
dismissBtn.isHidden = false

}