How can I animate the properties of my custom UIView? - swift

Question

I frequently need to round only two corners in a view, and sometimes need to use gradients. I've found that the common solution of using a CALayerMask is detrimental to performance, so I devised my own solution overriding drawRect(rect: CGRect). It works well, providing an easy way to round some or all corners, draw a border, and use both linear and radial gradient fills, even being able to set color stops for the gradients.
Unfortunately, when I try to animate these properties with UIView.animateWithDuration, my corners, gradients, and borders don't animate. Rather, they look "stretched" in the initial state, then animate to the final state. I've read that this can be solved with CALayer animation, but I'm not quite clear on the nature of the problem. Is there a way I can solve this as the class is now? If not, when is drawRect(rect: CGRect) preferable to drawLayer(layer: CALayer, inContext ctx: CGContext)?
I'm also open to general suggestions on improving this class.
AppocalypseUI.swift (provides support functions for UI operations)
//
// AppocalypseUI.swift
// Soapbox
//
// Created by Joseph Falcone on 6/2/16.
// Copyright © 2016 Joseph Falcone. All rights reserved.
//
import UIKit
class AppocalypseUI: NSObject
{
/// Generates an array of CGFloat values ranging from 0.0-1.0 which represent the color stops in a gradient
class func makeLinearColorStops(numStops:Int) -> [CGFloat]
{
assert(numStops >= 2, "Must have at least two color stops.")
let stepIncrement = 1.0/Double(numStops-1)
var returnArr : [CGFloat] = []
// The first stop is always 0
returnArr += [0.0]
for i in 1 ..< numStops-1
{
let stepVal = stepIncrement*Double(i)
let stepFactor = CGFloat(fmod(stepVal, 1.0))
returnArr += [stepFactor]
}
// The last stop is always 1
returnArr += [1.0]
// Fini
return returnArr
}
/// Returns the stop colors in an array
class func colorsAlongArray(colorArr:[UIColor], steps:Int) -> [UIColor]
{
let arrCount = colorArr.count
let stepIncrement = Double(arrCount)/Double(steps)
var returnArr : [UIColor] = []
for i in 0..<steps
{
let stepVal = stepIncrement*Double(i)
let stepFactor = CGFloat(fmod(stepVal, 1.0))
let stepIndex1 = Int(floor(stepVal/1.0))
var stepIndex2 = Int(ceil(stepVal/1.0))
if(stepIndex2 > arrCount-1)
{stepIndex2 = arrCount-1}
let color1 = colorArr[stepIndex1]
let color2 = colorArr[stepIndex2]
let color = colorByInterpolatingColors(color1, color2: color2, factor: stepFactor)
returnArr += [color]
}
return returnArr
}
/// Returns a color between two colors on a gradient
class func colorByInterpolatingColors(color1:UIColor, color2:UIColor, factor:CGFloat) -> UIColor
{
let startComponent = CGColorGetComponents(color1.CGColor)
let endComponent = CGColorGetComponents(color2.CGColor)
let startAlpha = CGColorGetAlpha(color1.CGColor)
let endAlpha = CGColorGetAlpha(color2.CGColor)
let r = startComponent[0] + (endComponent[0] - startComponent[0]) * factor
let g = startComponent[1] + (endComponent[1] - startComponent[1]) * factor
let b = startComponent[2] + (endComponent[2] - startComponent[2]) * factor
let a = startAlpha + (endAlpha - startAlpha) * factor
return UIColor(red: r, green: g, blue: b, alpha: a)
}
/* No longer needed
class func getFloatArrayFromNSNumbers(numbers:[NSNumber]) -> [CGFloat]
{
var returnArr : [CGFloat] = []
for number in numbers
{
returnArr += [CGFloat(number.floatValue)]
}
return returnArr
}
*/
/// Returns an array containing the RGBA components of an array of colors
class func getFloatArrayFromUIColors(colors:[UIColor]) -> [CGFloat]
{
var returnArr : [CGFloat] = []
for color : UIColor in colors
{
var red : CGFloat = 0.0
var green : CGFloat = 0.0
var blue : CGFloat = 0.0
var alpha : CGFloat = 0.0
color.getRed(&red, green: &green, blue: &blue, alpha: &alpha)
/*
// This check and backup should probably be implemented later, but it seems to fail when it shouldn't...probably improper use of optionals
if(color?.getRed(&red, green: &green, blue: &blue , alpha: &alpha) == nil)
{
// If for some reason the above function call fails, try this method of getting RGBA instead
let components = CGColorGetComponents(color?.CGColor)
red = components[0]
green = components[1]
blue = components[2]
alpha = components[3]
}
*/
returnArr += [red, green, blue, alpha]
}
return returnArr
}
/// Returns a path for a rectangle with rounded corners
class func newPathForRoundedRect(rect:CGRect, radiusTL radTL:CGFloat, radiusTR radTR:CGFloat, radiusBL radBL:CGFloat, radiusBR radBR:CGFloat, edges:UIRectEdge = .All) -> CGPathRef
{
let retPath = CGPathCreateMutable()
// Convenience
let rectL = rect.origin.x
let rectR = rect.origin.x+rect.size.width
let rectT = rect.origin.y
let rectB = rect.origin.y+rect.size.height
// Starting from the top left arc, move clockwise
let p1 = CGPointMake(rectL , rectT+radTL)
let p2 = CGPointMake(rectL+radTL, rectT)
let p3 = CGPointMake(rectR-radTR, rectT)
let p4 = CGPointMake(rectR , rectT+radTR)
let p5 = CGPointMake(rectR , rectB-radBR)
let p6 = CGPointMake(rectR-radBR, rectB)
let p7 = CGPointMake(rectL+radBL, rectB)
let p8 = CGPointMake(rectL , rectB-radBL)
let c1 = CGPointMake(rect.origin.x , rect.origin.y)
let c2 = CGPointMake(rect.origin.x+rect.size.width , rect.origin.y)
let c3 = CGPointMake(rect.origin.x+rect.size.width , rect.origin.y+rect.size.height)
let c4 = CGPointMake(rect.origin.x , rect.origin.y+rect.size.height)
if(edges.contains(.All) || (edges.contains(.Left) && edges.contains(.Right) && edges.contains(.Top) && edges.contains(.Bottom)))
{
CGPathMoveToPoint(retPath, nil, p1.x, p1.y)
CGPathAddArcToPoint (retPath, nil, c1.x, c1.y, p2.x, p2.y, radTL)
CGPathAddLineToPoint(retPath, nil, p3.x, p3.y)
CGPathAddArcToPoint (retPath, nil, c2.x, c2.y, p4.x, p4.y, radTR)
CGPathAddLineToPoint(retPath, nil, p5.x, p5.y)
CGPathAddArcToPoint (retPath, nil, c3.x, c3.y, p6.x, p6.y, radBR)
CGPathAddLineToPoint(retPath, nil, p7.x, p7.y)
CGPathAddArcToPoint (retPath, nil, c4.x, c4.y, p8.x, p8.y, radBL)
CGPathAddLineToPoint(retPath, nil, p1.x, p1.y)
CGPathCloseSubpath(retPath)
return retPath
}
if(edges.contains(.Top))
{
CGPathMoveToPoint(retPath, nil, p1.x, p1.y)
CGPathAddArcToPoint (retPath, nil, c1.x, c1.y, p2.x, p2.y, radTL)
CGPathAddLineToPoint(retPath, nil, p3.x, p3.y)
CGPathAddArcToPoint (retPath, nil, c2.x, c2.y, p4.x, p4.y, radTR)
}
if(edges.contains(.Right))
{
CGPathMoveToPoint(retPath, nil, p3.x, p3.y)
CGPathAddArcToPoint (retPath, nil, c2.x, c2.y, p4.x, p4.y, radTR)
CGPathAddLineToPoint(retPath, nil, p5.x, p5.y)
CGPathAddArcToPoint (retPath, nil, c3.x, c3.y, p6.x, p6.y, radBR)
}
if(edges.contains(.Bottom))
{
CGPathMoveToPoint(retPath, nil, p5.x, p5.y)
CGPathAddArcToPoint (retPath, nil, c3.x, c3.y, p6.x, p6.y, radBR)
CGPathAddLineToPoint(retPath, nil, p7.x, p7.y)
CGPathAddArcToPoint (retPath, nil, c4.x, c4.y, p8.x, p8.y, radBL)
}
if(edges.contains(.Left))
{
CGPathMoveToPoint(retPath, nil, p7.x, p7.y)
CGPathAddArcToPoint (retPath, nil, c4.x, c4.y, p8.x, p8.y, radBL)
CGPathAddLineToPoint(retPath, nil, p1.x, p1.y)
CGPathAddArcToPoint (retPath, nil, c1.x, c1.y, p2.x, p2.y, radTL)
}
return retPath
}
}
JFStylishView.swift
//
// JFStylishView.swift
// Soapbox
//
// Created by Joseph Falcone on 6/2/16.
// Copyright © 2016 Joseph Falcone. All rights reserved.
//
import UIKit
enum GradientType
{
case Linear
case Radial
}
private enum BackgroundFillType
{
case Solid
case Gradient
}
class JFStylishView : UIView
{
// Rounded Corners
var cornerTL : CGFloat = 0.0
var cornerTR : CGFloat = 0.0
var cornerBR : CGFloat = 0.0
var cornerBL : CGFloat = 0.0
// Border
var borderWidth : CGFloat = 4.0
var borderColor = UIColor.greenColor()
// Colors
private var trueBackgroundColor = UIColor.clearColor() // The backgroundColor property has to be clear so that the layer doesn't draw behind the clipping area, so we use this to track what the user wants
private var bgColors : [CGFloat] = [] // array of colors used in drawrect
// Gradient points
private var gradientStart = CGPointMake(0.5, 0.0)
private var gradientEnd = CGPointMake(0.5, 1.0)
private var gradientColorStops : [CGFloat] = []
// Gradient type
private var gradientType : GradientType = .Linear
// Background Mode
private var backgroundFillType : BackgroundFillType = .Solid
// var shadowLayer: CAShapeLayer! // Not ready for this yet
// MARK: Initialization
override init(frame: CGRect)
{
super.init(frame:frame)
}
required init?(coder aDecoder: NSCoder)
{
super.init(coder:aDecoder)
}
override func awakeFromNib()
{
super.awakeFromNib()
}
func initStylishStuff()
{
cornerTL = 0.0
}
// MARK: Color
private func getFillType() -> BackgroundFillType
{
// Rather than keeping a variable for this that gets set everywhere, we'll just use this getter to figure out what type we are using.
// Of course, if I get sloppy and don't make the unused elements empty when setting another fill parameter, this could produce a bug.
// RULES
// If using a gradient, trueBackgroundColor will be clear
// If using solid, bgColors will be empty
// If patterns are ever added, the above will be empty
if(bgColors.count == 0)
{return .Solid}
if(trueBackgroundColor == UIColor.clearColor())
{return .Gradient}
// Default
return .Solid
}
override var backgroundColor: UIColor?
{
get
{
return trueBackgroundColor
}
set
{
trueBackgroundColor = backgroundColor!
super.backgroundColor = UIColor.clearColor()
//bgColorArr = []
bgColors = []
backgroundFillType = .Solid
}
/*
// Property observer - whenever the background color is
didSet
{
bgColorArr = []
bgColors = []
// bgColorArr = [backgroundColor!]
// bgColors = AppocalypseUI.getFloatArrayFromUIColors([backgroundColor!, backgroundColor!])
}
*/
}
// // Convenient...maybe we shouldn't include this?
// func setBackgroundGradient(topColor:UIColor, bottomColor:UIColor)
// {
// bgColorArr = [topColor, bottomColor]
// bgColors = AppocalypseUI.getFloatArrayFromUIColors([topColor, bottomColor])
// }
// Default is linear, top to bottom
// startPoint, endPoint should be coordinates of 0.0-1.0
func setBackgroundGradient(colors:[UIColor], stops:[CGFloat]? = nil, startPoint:CGPoint?=nil, endPoint:CGPoint?=nil, type:GradientType = .Linear)
{
assert(colors.count > 1, "At least two colors must be specified.")
// We won't be using the backgroundColor property when drawing a gradient
trueBackgroundColor = UIColor.clearColor()
// Calculate the stops if they were not specified
var stops = stops // arguments are immutable, but we can declare a variable with the same name
if(stops == nil)
{
stops = AppocalypseUI.makeLinearColorStops(colors.count)
}
// Provide default start and end points if necessary
gradientType = type
switch type
{
case .Linear: // top to bottom
gradientStart = startPoint == nil ? CGPointZero : startPoint!
gradientEnd = endPoint == nil ? CGPointMake(0, 1.0) : endPoint!
case .Radial: // center to top
gradientStart = startPoint == nil ? CGPointMake(0.5, 0.5) : startPoint!
gradientEnd = endPoint == nil ? CGPointMake(0.5, 0) : endPoint!
}
assert(colors.count == stops?.count, "The number of colors and stops must be equal.")
//bgColorArr = colors
bgColors = AppocalypseUI.getFloatArrayFromUIColors(colors)
gradientColorStops = stops!
}
/*
override func layoutSubviews()
{
super.layoutSubviews()
if shadowLayer == nil
{
shadowLayer = CAShapeLayer()
shadowLayer.path = UIBezierPath(roundedRect: bounds, cornerRadius: 12).CGPath
//shadowLayer.fillColor = UIColor.whiteColor().CGColor
shadowLayer.fillColor = UIColor.clearColor().CGColor
shadowLayer.shadowColor = UIColor.darkGrayColor().CGColor
shadowLayer.shadowPath = shadowLayer.path
shadowLayer.shadowOffset = CGSize(width: 2.0, height: 2.0)
shadowLayer.shadowOpacity = 0.8
shadowLayer.shadowRadius = 2
//layer.insertSublayer(shadowLayer, atIndex: 0)
layer.insertSublayer(shadowLayer, below: nil) // also works
}
}
*/
// MARK: Drawing
// override func drawLayer(layer: CALayer, inContext ctx: CGContext) {
//
// }
override func drawRect(rect: CGRect)
{
// Get the current context
let context = UIGraphicsGetCurrentContext()
// Make the background gradient
let baseSpace = CGColorSpaceCreateDeviceRGB();
let gradient = CGGradientCreateWithColorComponents(baseSpace, bgColors, gradientColorStops, gradientColorStops.count);
// Set the border color and stroke
CGContextSetLineWidth(context, borderWidth);
CGContextSetStrokeColorWithColor(context, borderColor.CGColor);
// Fill in the background, inset by the border
let bgRect = CGRectMake(bounds.origin.x+borderWidth , bounds.origin.y+borderWidth , bounds.size.width-borderWidth*2, bounds.size.height-borderWidth*2);
let borderRect = CGRectMake(bounds.origin.x+borderWidth/2, bounds.origin.y+borderWidth/2, bounds.size.width-borderWidth , bounds.size.height-borderWidth);
let bgPath = AppocalypseUI.newPathForRoundedRect(bgRect, radiusTL: cornerTL, radiusTR: cornerTR, radiusBL: cornerBL, radiusBR: cornerBR)
let borderPath = AppocalypseUI.newPathForRoundedRect(borderRect, radiusTL: cornerTL, radiusTR: cornerTR, radiusBL: cornerBL, radiusBR: cornerBR)
CGContextStrokePath(context)
// Background
CGContextSaveGState(context); // Saves the state from before we clipped to the path
CGContextAddPath(context, bgPath);
CGContextClip(context); // Makes the background fill only the path
switch getFillType()
{
case .Gradient:
let gradientStartInPoints = CGPointMake(gradientStart.x*bounds.size.width, gradientStart.y*bounds.size.height);
let gradientEndInPoints = CGPointMake(gradientEnd.x*bounds.size.width, gradientEnd.y*bounds.size.height);
switch(gradientType)
{
case .Linear:
CGContextDrawLinearGradient(context, gradient, gradientStartInPoints, gradientEndInPoints, []); // Draw a vertical gradient
case .Radial:
// A radial gradient might not fill the layer...first, fill it with the end color
UIColor(red: bgColors[bgColors.count-4], green: bgColors[bgColors.count-3], blue: bgColors[bgColors.count-2], alpha: bgColors[bgColors.count-1]).setFill()
CGContextAddPath(context, bgPath); // Not sure why I need this...TODO: Investigate
CGContextFillPath(context)
let endRadius = hypot(gradientStartInPoints.x-gradientEndInPoints.x, gradientStartInPoints.y-gradientEndInPoints.y)
CGContextDrawRadialGradient(context, gradient, gradientStartInPoints, 0, gradientStartInPoints, endRadius, [])
}
case .Solid:
trueBackgroundColor.setFill()
CGContextFillPath(context)
}
CGContextRestoreGState(context); // Now we are no longer clipped to the path
// Border
CGContextAddPath(context, borderPath);
CGContextStrokePath(context);
}
// MARK: Convenience
func removeAllSubviews()
{
for view in subviews
{view.removeFromSuperview()}
}
}

Answer 1

You can create a CAGradientLayer, then add mask with only two corner radius to it. Then you can animate the transform using Core Animation, or UIView transform animation also should work if you put the layer in UIView.
CAGradientLayer * rectangleGradient = [CAGradientLayer layer];
rectangleGradient.colors = #[(id)[UIColor greenColor].CGColor, (id)[UIColor orangeColor].CGColor];
rectangleGradient.startPoint = CGPointMake(0.5, 0);
rectangleGradient.endPoint = CGPointMake(0.5, 1);
rectangleMask.path = maskPath;
////The animation
CABasicAnimation * theTransformAnim = [CABasicAnimation animationWithKeyPath:#"transform"];
theTransformAnim.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];;
theTransformAnim.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(2, 2, 1)];;
theTransformAnim.duration = 1;
[rectangleGradient addAnimation:theTransformAnim];