Swift 3 draw uiimage programmatically

Question

I don't have experience in Core Graphics but I need to draw a dynamic uiimage that look like these:

(Actually I want the grey area to be clear. So the red color will look like floating)

This is the code I tried:

public extension UIImage {

    public convenience init?(color: UIColor, size: CGSize = CGSize(width: 27, height: 5), isWhole: Bool = true) {
        let totalHeight: CGFloat = 5.0
        let topRectHeight: CGFloat = 1.0

        //if (isWhole) {
        let topRect = CGRect(origin: .zero, size: CGSize(width: size.width, height: topRectHeight))
        UIGraphicsBeginImageContextWithOptions(topRect.size, false, 0.0)
        color.setFill()
        UIRectFill(topRect)

        let bottomRect = CGRect(origin: CGPoint(x: 0, y: topRectHeight), size: CGSize(width: size.width, height: totalHeight - topRectHeight))
        UIGraphicsBeginImageContextWithOptions(bottomRect.size, false, 0.0)
        UIColor.blue.setFill()
        UIRectFill(bottomRect)

        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        guard let cgImage = image?.cgImage else { return nil }
        self.init(cgImage: cgImage)
    }

need to be uiimage. as the library function im calling needs uiimage as input. — iadgotstacked
– iadgotstacked, Commented Jul 10, 2017 at 15:32
I'm adding a new answer. I know you've accepted one already, but this may be a good alternative. It turns any UIView into a UIImage. — user7014451
– user7014451, Commented Jul 10, 2017 at 16:01

Svetoslav Bramchev · Accepted Answer · 2017-07-12 14:18:27Z

1

Here is example you can have first image if you set isWhole property to false and have second image if you set it to true. You can paste this code in viewDidLoad to test and play with it.

    var isWhole = false
    UIGraphicsBeginImageContextWithOptions(CGSize.init(width: 27, height: 5), false,0.0)
    var context = UIGraphicsGetCurrentContext()
    context?.setFillColor(UIColor.red.cgColor)
    if(context != nil){
        if(isWhole){
            context?.fill(CGRect(x: 0, y: 0, width: 27, height: 2.5))
        }
        else{
            context?.fill(CGRect(x: 0, y: 0, width: 13.5, height: 2.5))
        }
        context?.setFillColor(UIColor.gray.cgColor)
        context?.fill(CGRect(x: 0, y: 2.5, width: 27, height: 2.5))
    }


    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    var imageView = UIImageView(frame: CGRect(x: 100, y: 200, width: 27, height: 5))
    imageView.image = newImage
    self.view.addSubview(imageView)
    UIGraphicsEndImageContext()

If you need your red rectangle to be with rounder corners just change fill(rect:CGRect) with path like this:

    if(isWhole){
        context?.addPath(CGPath(roundedRect: CGRect(x: 0, y: 0, width: 27, height: 2.5), cornerWidth: 1, cornerHeight: 1, transform: nil))
        context?.fillPath()
    }

edited Jul 12, 2017 at 14:18

answered Jul 10, 2017 at 15:37

Svetoslav Bramchev

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4 Comments

iadgotstacked Over a year ago

woow! very close to what I want. Thanks @svetoslav. I'll play with this to my desired uiimage

Svetoslav Bramchev Over a year ago

Yes i know that it is not exactly the same ,but i think it will be easy for you to manage with it now. If you have question i am here to answer

iadgotstacked Over a year ago

Hi svetoslav. How to make the edges of the red rectangle rounded?

iadgotstacked Over a year ago

thanks. It is working! but is it possible to only roundup one of the edges? and not both?

user7014451 · Accepted Answer · 2017-07-10 16:01:31Z

1

I know you said in your comments that you can't use UIViews, but what you want "looks" easily done through views. Why not do that, then simply turn it into a UIImage?

override func viewDidLoad() {
    super.viewDidLoad()

    let imageContainer = UIView(frame: CGRect(x: 30, y: 40, width: 110, height: 60))
    imageContainer.backgroundColor = view.backgroundColor
    view.addSubview(imageContainer)

    let redView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 30))
    redView.backgroundColor = UIColor.red
    let grayView = UIView(frame: CGRect(x: 10, y: 30, width: 100, height: 30))
    grayView.backgroundColor = UIColor.gray
    imageContainer.addSubview(redView)
    imageContainer.addSubview(grayView)

    let imageView = UIImageView(frame: CGRect(x: 100, y: 140, width: 200, height: 200))
    imageView.contentMode = .scaleAspectFit
    imageView.image = createImage(imageContainer)

    view.addSubview(imageView)
}

func createImage(_ view: UIView) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(
        CGSize(width: view.frame.width, height: view.frame.height), true, 1)
    view.layer.render(in: UIGraphicsGetCurrentContext()!)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image!
}

answered Jul 10, 2017 at 16:01

user7014451

1 Comment

iadgotstacked Over a year ago

Thanks for this alternative. Sorry I cant upvote ur answer not enough reputation

genghiskhan · Accepted Answer · 2017-07-10 15:36:41Z

0

I'd recommend creating two paths in the first context that you create, i.e.

let topPath = UIBezierPath(rect: topRect)
color.setFill()
topPath.fill()

let bottomPath = UIBezierPath(rect: bottomRect)
UIColor.blue.setFill()
bottomPath.fill()

Then you can get the image from the current context.

answered Jul 10, 2017 at 15:36

genghiskhan

1,15912 silver badges21 bronze badges

1 Comment

iadgotstacked Over a year ago

sorry bro. noob on core graphics here. I dont understand this =/

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