Swift extension example

Question

I was originally wanting to know how to make something like this

UIColor.myCustomGreen

so that I could define my own colors and use them th

Answer 1

UIColor+util.swift

import UIKit


extension UIColor{


    class func getCustomBlueColor() -> UIColor
    {
        return UIColor(red:0.043, green:0.576 ,blue:0.588 , alpha:1.00)
    }

    func getNameofColour() ->String
    {
        return "myOrange"
    }

}

Usage :

NSLog("\(UIColor.getCustomBlueColor())")
let color=UIColor(red:0.043, green:0.576 ,blue:0.588 , alpha:1.00);
NSLog(color.getNameofColour())

I hope you see that what is difference . One of Function starting with class func another one starting only func . you can use which you like.

Answer 2

Here is an extension example of an eye catching animation effect that works with cells from UITableView. Each cell grows from a point source to normal size as you scroll a UITableView. Adjust the animation timing as desired.

Since each cell shows up with a little time stagger while scrolling, the effect ripples nicely! See this 15 second clip that showcases the effect : https://www.youtube.com/watch?v=BVeQpno56wU&feature=youtu.be

extension UITableViewCell {

    func growCellDuringPresentation(thisCell : UITableViewCell) {

        thisCell.transform = CGAffineTransform(scaleX: 0.01, y: 0.01)

        UIView.animate(withDuration: TimeInterval(0.35), delay: 0.0, options: UIView.AnimationOptions.allowUserInteraction,   animations: {

            thisCell.transform = CGAffineTransform(scaleX: 1, y: 1)

        }, completion: nil)

    }
}

To use the extension you make a call to it just before the cell is returned in cellForRowAt, like shown below :

            cell.growCellDuringPresentation(thisCell: cell)
            return cell

Note this same method works when returning cells for a collection view.

Here is an extension that works exactly the same, except that it rotates the cells during presentation :

extension UITableViewCell {

    func rotateCellDuringPresentation(thisCell : UITableViewCell) {

        thisCell.transform = CGAffineTransform(rotationAngle: .pi)

        UIView.animate(withDuration: TimeInterval(0.35), delay: 0.0, options: UIView.AnimationOptions.allowUserInteraction,   animations: {

            thisCell.transform = CGAffineTransform(rotationAngle: 0)

        }, completion: nil)

    }
}

It's called similarly :

            cell.rotateCellDuringPresentation(thisCell: cell)
            return cell

Here is an extension along the same lines that translates the cells in the X direction

extension UITableViewCell {

    func translateCellDuringPresentation(thisCell : UITableViewCell) {

        thisCell.layer.transform = CATransform3DMakeTranslation(-300, 0, 0)

        UIView.animate(withDuration: TimeInterval(0.5), delay: 0.0, options: UIView.AnimationOptions.allowUserInteraction,   animations: {

            thisCell.layer.transform = CATransform3DMakeTranslation(0, 0, 0)

        }, completion: nil)

    }
}

It's called similarly :

            cell.translateCellDuringPresentation(thisCell: cell)
            return cell