Animate the reveal of a UIView from the leading side.

UIView+RevealFromLeading.swift

//
//  UIView+RevealFromLeading.swift
//  VitocDev
//
//  Created by Bogdan Vitoc on 5/12/16.
//  Copyright © 2016 VitocDev. All rights reserved.
//

import UIKit

extension UIView {
    /**
     Animate the reveal of a UIView from the leading side.
     
     - parameter duration:	duration of animation
     - warning: Will overwrite any existing `maskViews`.
     */
    func revealFromLeading(duration: NSTimeInterval) {
        maskView = UIView(frame: CGRectMake(0,0,0, CGRectGetHeight(self.frame)))
        maskView?.backgroundColor = .whiteColor()
        UIView.animateWithDuration(duration) {
            self.maskView?.frame.size.width = CGRectGetWidth(self.frame)
        }
    }
}