I must admit I have no clue how to do this in iOS -
Here's some code that makes a nice dotted line:
Now, I want that line to "run" upwards:
So, every one second it will move upwards by, itemLength * 2.0.
Of course, it would wrap around top to bottom.
So, DottedVertical should just do this completely on its own.
Really, how do you do this in iOS?
It would be great if the solution is general and will "scroll" any I suppose layer or drawn thing.
In say a game engine it's trivial, you just animate the offset of the texture. Can you perhaps offset the layer, or something, in iOS?
What's the best way?
I guess you'd want to use the GPU (layer animation right?) to avoid melting the cpu.
#IBDesignable class DottedVertical: UIView {
#IBInspectable var dotColor: UIColor = UIColor.faveColor
override func draw(_ rect: CGRect) {
// say you want 8 dots, with perfect fenceposting:
let totalCount = 8 + 8 - 1
let fullHeight = bounds.size.height
let width = bounds.size.width
let itemLength = fullHeight / CGFloat(totalCount)
let beginFromTop = !lowerHalfOnly ? 0.0 : (fullHeight * 8.0 / 15.0)
let top = CGPoint(x: width/2, y: beginFromTop)
let bottom = CGPoint(x: width/2, y: fullHeight)
let path = UIBezierPath()
path.move(to: top)
path.addLine(to: bottom)
path.lineWidth = width
let dashes: [CGFloat] = [itemLength, itemLength]
path.setLineDash(dashes, count: dashes.count, phase: 0)
dotColor.setStroke()
path.stroke()
}
(Bonus - if you had a few of these on screen, they'd have to be synced of course. There'd need to be a "sync" call that starts the running animation, so you can start them all at once with a notification or other message.)
Hate to answer my own question, here's a copy and paste solution based on the Men's suggestions above!
Good one! Superb effect...
#IBDesignable class DottedVertical: UIView {
#IBInspectable var dotColor: UIColor = sfBlack6 { didSet {setup()} }
override func layoutSubviews() { setup() }
var s:CAShapeLayer? = nil
func setup() {
// say you want 8 dots, with perfect fenceposting:
- calculate exactly as in the example in the question above -
// marching ants...
if (s == nil) {
s = CAShapeLayer()
self.layer.addSublayer(s!)
}
s!.strokeColor = dotColor.cgColor
s!.fillColor = backgroundColor?.cgColor
s!.lineWidth = width
let ns = NSNumber(value: Double(itemLength))
s!.lineDashPattern = [ns, ns]
let path = CGMutablePath()
path.addLines(between: [top, bottom])
s!.path = path
let anim = CABasicAnimation(keyPath: "lineDashPhase")
anim.fromValue = 0
anim.toValue = ns + ns
anim.duration = 1.75 // seconds
anim.repeatCount = Float.greatestFiniteMagnitude
s!.add(anim, forKey: nil)
self.layer.addSublayer(s!)
}
}
Related
I am trying to build a UIView that has a few UIImageViews arranged in a circular, overlapping manner (see image below). Let's say we have N images. Drawing out the first N - 1 is easy, just use sin/cos functions to arrange the centers of the UIImageViews around a circle. The problem is with the last image that seemingly has two z-index values! I know this is possible since kik messenger has similar group profile photos.
The best idea I have come up so far is taking the last image, split into something like "top half" and "bottom half" and assign different z-values for each. This seems doable when the image is the left-most one, but what happens if the image is the top most? In this case, I would need to split left and right instead of top and bottom.
Because of this problem, it's probably not top, left, or right, but more like a split across some imaginary axis from the center of the overall facepile through the center of the UIImageView. How would I do that?!
Below Code Will Layout UIImageView's in Circle
You would need to import SDWebImage and provide some image URLs to run the code below.
import Foundation
import UIKit
import SDWebImage
class EventDetailsFacepileView: UIView {
static let dimension: CGFloat = 66.0
static let radius: CGFloat = dimension / 1.68
private var profilePicViews: [UIImageView] = []
var profilePicURLs: [URL] = [] {
didSet {
updateView()
}
}
func updateView() {
self.profilePicViews = profilePicURLs.map({ (profilePic) -> UIImageView in
let imageView = UIImageView()
imageView.sd_setImage(with: profilePic)
imageView.roundImage(imageDimension: EventDetailsFacepileView.dimension, showsBorder: true)
imageView.sd_imageTransition = .fade
return imageView
})
self.profilePicViews.forEach { (imageView) in
self.addSubview(imageView)
}
self.setNeedsLayout()
self.layer.borderColor = UIColor.green.cgColor
self.layer.borderWidth = 2
}
override func layoutSubviews() {
super.layoutSubviews()
let xOffset: CGFloat = 0
let yOffset: CGFloat = 0
let center = CGPoint(x: self.bounds.size.width / 2, y: self.bounds.size.height / 2)
let radius: CGFloat = EventDetailsFacepileView.radius
let angleStep: CGFloat = 2 * CGFloat(Double.pi) / CGFloat(profilePicViews.count)
var count = 0
for profilePicView in profilePicViews {
let xPos = center.x + CGFloat(cosf(Float(angleStep) * Float(count))) * (radius - xOffset)
let yPos = center.y + CGFloat(sinf(Float(angleStep) * Float(count))) * (radius - yOffset)
profilePicView.frame = CGRect(origin: CGPoint(x: xPos, y: yPos),
size: CGSize(width: EventDetailsFacepileView.dimension, height: EventDetailsFacepileView.dimension))
count += 1
}
}
override func sizeThatFits(_ size: CGSize) -> CGSize {
let requiredSize = EventDetailsFacepileView.dimension + EventDetailsFacepileView.radius
return CGSize(width: requiredSize,
height: requiredSize)
}
}
I don't think you'll have much success trying to split images to get over/under z-indexes.
One approach is to use masks to make it appear that the image views are overlapped.
The general idea would be:
subclass UIImageView
in layoutSubviews()
apply cornerRadius to layer to make the image round
get a rect from the "overlapping view"
convert that rect to local coordinates
expand that rect by the desired width of the "outline"
get an oval path from that rect
combine it with a path from self
apply it as a mask layer
Here is an example....
I was not entirely sure what your sizing calculations were doing... trying to use your EventDetailsFacepileView as-is gave me small images in the lower-right corner of the view?
So, I modified your EventDetailsFacepileView in a couple ways:
uses local images named "pro1" through "pro5" (you should be able to replace with your SDWebImage)
uses auto-layout constraints instead of explicit frames
uses MyOverlapImageView class to handle the masking
Code - no #IBOutlet connections, so just set a blank view controller to OverlapTestViewController:
class OverlapTestViewController: UIViewController {
let facePileView = MyFacePileView()
override func viewDidLoad() {
super.viewDidLoad()
facePileView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(facePileView)
facePileView.dimension = 120
let sz = facePileView.sizeThatFits(.zero)
let g = view.safeAreaLayoutGuide
NSLayoutConstraint.activate([
facePileView.widthAnchor.constraint(equalToConstant: sz.width),
facePileView.heightAnchor.constraint(equalTo: facePileView.widthAnchor),
facePileView.centerXAnchor.constraint(equalTo: g.centerXAnchor),
facePileView.centerYAnchor.constraint(equalTo: g.centerYAnchor),
])
facePileView.profilePicNames = [
"pro1", "pro2", "pro3", "pro4", "pro5"
]
}
}
class MyFacePileView: UIView {
var dimension: CGFloat = 66.0
lazy var radius: CGFloat = dimension / 1.68
private var profilePicViews: [MyOverlapImageView] = []
var profilePicNames: [String] = [] {
didSet {
updateView()
}
}
func updateView() {
self.profilePicViews = profilePicNames.map({ (profilePic) -> MyOverlapImageView in
let imageView = MyOverlapImageView()
if let img = UIImage(named: profilePic) {
imageView.image = img
}
return imageView
})
// add MyOverlapImageViews to self
// and set width / height constraints
self.profilePicViews.forEach { (imageView) in
self.addSubview(imageView)
imageView.translatesAutoresizingMaskIntoConstraints = false
imageView.widthAnchor.constraint(equalToConstant: dimension).isActive = true
imageView.heightAnchor.constraint(equalTo: imageView.widthAnchor).isActive = true
}
// start at "12 o'clock"
var curAngle: CGFloat = .pi * 1.5
// angle increment
let incAngle: CGFloat = ( 360.0 / CGFloat(self.profilePicViews.count) ) * .pi / 180.0
// calculate position for each image view
// set center constraints
self.profilePicViews.forEach { imgView in
let xPos = cos(curAngle) * radius
let yPos = sin(curAngle) * radius
imgView.centerXAnchor.constraint(equalTo: centerXAnchor, constant: xPos).isActive = true
imgView.centerYAnchor.constraint(equalTo: centerYAnchor, constant: yPos).isActive = true
curAngle += incAngle
}
// set "overlapView" property for each image view
let n = self.profilePicViews.count
for i in (1..<n).reversed() {
self.profilePicViews[i].overlapView = self.profilePicViews[i-1]
}
self.profilePicViews[0].overlapView = self.profilePicViews[n - 1]
self.layer.borderColor = UIColor.green.cgColor
self.layer.borderWidth = 2
}
override func sizeThatFits(_ size: CGSize) -> CGSize {
let requiredSize = dimension * 2.0 + radius / 2.0
return CGSize(width: requiredSize,
height: requiredSize)
}
}
class MyOverlapImageView: UIImageView {
// reference to the view that is overlapping me
weak var overlapView: MyOverlapImageView?
// width of "outline"
var outlineWidth: CGFloat = 6
override func layoutSubviews() {
super.layoutSubviews()
// make image round
layer.cornerRadius = bounds.size.width * 0.5
layer.masksToBounds = true
let mask = CAShapeLayer()
if let v = overlapView {
// get bounds from overlapView
// converted to self
// inset by outlineWidth (negative numbers will make it grow)
let maskRect = v.convert(v.bounds, to: self).insetBy(dx: -outlineWidth, dy: -outlineWidth)
// oval path from mask rect
let path = UIBezierPath(ovalIn: maskRect)
// path from self bounds
let clipPath = UIBezierPath(rect: bounds)
// append paths
clipPath.append(path)
mask.path = clipPath.cgPath
mask.fillRule = .evenOdd
// apply mask
layer.mask = mask
}
}
}
Result:
(I grabbed random images by searching google for sample profile pictures)
I have a custom UIView where I add a CAShapeLayer as a direct sublayer of the view's layer:
private let arcShapeLayer = CAShapeLayer()
The CAShapeLayer has the following properties (the border is to visualize more easily the animation) declared in the awakeFromNib:
arcShapeLayer.lineWidth = 2.0
arcShapeLayer.strokeColor = UIColor.black.cgColor
arcShapeLayer.fillColor = UIColor.lightGray.cgColor
arcShapeLayer.masksToBounds = false
layer.masksToBounds = false
layer.addSublayer(arcShapeLayer)
I declare the frame of the arcShapeLayer in the layoutSubviews:
arcShapeLayer.frame = layer.bounds
Then I have the following function where I pass a certain percentage (from the ViewController) in order to achieve the arc effect after some dragging. Simply put I add a quadCurve at the bottom of the layer:
func configureArcPath(curvePercentage: CGFloat) -> CGPath {
let path = UIBezierPath()
path.move(to: CGPoint.zero)
path.addLine(to:
CGPoint(
x: arcShapeLayer.bounds.minX,
y: arcShapeLayer.bounds.maxY
)
)
path.addQuadCurve(
to:
CGPoint(
x: arcShapeLayer.bounds.maxX,
y: arcShapeLayer.bounds.maxY
),
controlPoint:
CGPoint(
x: arcShapeLayer.bounds.midX,
y: arcShapeLayer.bounds.maxY + arcShapeLayer.bounds.maxY * (curvePercentage * 0.4)
)
)
path.addLine(to:
CGPoint(
x: arcShapeLayer.bounds.maxX,
y: arcShapeLayer.bounds.minY
)
)
path.close()
return path.cgPath
}
Then I try to animate with a spring effect the arc with the following code:
func animateArcPath() {
let springAnimation = CASpringAnimation(keyPath: "path")
springAnimation.initialVelocity = 10
springAnimation.mass = 10
springAnimation.duration = springAnimation.settlingDuration
springAnimation.fromValue = arcShapeLayer.path
springAnimation.toValue = configureArcPath(curvePercentage: 0.0)
springAnimation.fillMode = .both
arcShapeLayer.add(springAnimation, forKey: nil)
arcShapeLayer.path = configureArcPath(curvePercentage: 0.0)
}
The problem, as you can see in the video, is that the arc never overshoots. Although it oscillates between its original position and the rest position, the spring effect is never achieved.
What am I missing here?
I played around with this and I can report that you are absolutely right. It has nothing to do clamping at zero. The visible animation clamps at both extremes.
Let's say you supply a big mass value so that the overshoot should go way past the initial position of the convex bow on its return journey back to the start. Then what we see is that the animation clamps both at that original position and at the minimum you are trying to animate to. As the spring comes swinging between them, we see the animation happening between one extreme and the other, but as it reaches the max or min it just clamps there until it has had time to swing to its full extent and return.
I have to conclude that CAShapeLayer path doesn't like springing animations. This same point is raised at CAShapeLayer path spring animation not 'overshooting'
I was able to simulate the sort of look you're probably after by chaining normal basic animations:
Here's the code I used (based on your own code):
#IBAction func animateArcPath() {
self.animate(to:-1, in:0.5, from:arcShapeLayer.path!)
}
func animate(to arc:CGFloat, in time:Double, from current:CGPath) {
let goal = configureArcPath(curvePercentage: arc)
let anim = CABasicAnimation(keyPath: "path")
anim.duration = time
anim.fromValue = current
anim.toValue = goal
anim.delegate = self
anim.setValue(arc, forKey: "arc")
anim.setValue(time, forKey: "time")
anim.setValue(goal, forKey: "pathh")
arcShapeLayer.add(anim, forKey: nil)
}
func animationDidStop(_ anim: CAAnimation, finished flag: Bool) {
if let arc = anim.value(forKey:"arc") as? CGFloat,
let time = anim.value(forKey:"time") as? Double,
let p = anim.value(forKey:"pathh") {
if time < 0.05 {
return
}
self.animate(to:arc*(-0.5), in:time*0.5, from:p as! CGPath)
}
}
Core-Animation treats angles as described in this image:
(image from http://btk.tillnagel.com/tutorials/rotation-translation-matrix.html)
EDIT: Adding an animated gif to explain better what I'm needing:
I need to animate a slice to grow wider, starting at 300:315 degrees, and ending 300:060.
To create each slice I'm using this function:
extension CGFloat {
func toRadians() -> CGFloat {
return self * CGFloat(Double.pi) / 180.0
}
}
func createSlice(angle1:CGFloat, angle2:CGFloat) -> UIBezierPath! {
let path: UIBezierPath = UIBezierPath()
let width: CGFloat = self.frame.size.width/2
let height: CGFloat = self.frame.size.height/2
let centerToOrigin: CGFloat = sqrt((height)*(height)+(width)*(width));
let ctr: CGPoint = CGPoint(x: width, y: height)
path.move(to: ctr)
path.addArc( withCenter: ctr,
radius: centerToOrigin,
startAngle: CGFloat(angle1).toRadians(),
endAngle: CGFloat(angle2).toRadians(),
clockwise: true
)
path.close()
return path
}
I can now create the two slices and a sublayer with the smaller one, but I can't find how to proceed from this point:
func doStuff() {
path1 = self.createSlice(angle1: 300,angle2: 315)
path2 = self.createSlice(angle1: 300,angle2: 60)
let shapeLayer = CAShapeLayer()
shapeLayer.path = path1.cgPath
shapeLayer.fillColor = UIColor.cyan.cgColor
self.layer.addSublayer(shapeLayer)
I would highly appreciate any help here!
Only a single color
If you want to animate the angle of a solid color filled pie segment like the one in your question, then you can do it by animating the strokeEnd of a CAShapeLayer.
The "trick" here is to make a very wide line. More specifically, you can create a path that is just an arc (the dashed line in the animation below) at half of the intended radius and then giving it the full radius as its line width. When you animate stroking that line it looks like the orange segment below:
Depending on your use case, you can either:
create a path from one angle to the other angle and animate stroke end from 0 to 1
create a path for a full circle, set stroke start and stroke end to some fraction of the circle, and animate stroke end from the start fraction to the end fraction.
If your drawing is just a single color like this, then this will be the smallest solution to your problem.
However, if your drawing is more complex (e.g. also stroking the pie segment) then this solutions simply won't work and you'll have to do something more complex.
Custom drawing / Custom animations
If your drawing of the pie segment is any more complex, then you'll quickly find yourself having to create a layer subclass with custom animatable properties. Doing so is a bit more code - some of which might look a bit unusual1 - but not as scary as it might sound.
This might be one of those things that is still more convenient to do in Objective-C.
Dynamic properties
First, create a layer subclass with the properties you're going to need. In Objective-C parlance these properties should be #dynamic, i.e. not synthesized. This isn't the same as dynamic in Swift. Instead we have to use #NSManaged.
class PieSegmentLayer : CALayer {
#NSManaged var startAngle, endAngle, strokeWidth: CGFloat
#NSManaged var fillColor, strokeColor: UIColor?
// More to come here ...
}
This allows Core Animation to handle these properties dynamically allowing it to track changes and integrate them into the animation system.
Note: a good rule of thumb is that these properties should all be related to drawing / visual presentation of the layer. If they aren't then it's quite likely that they don't belong on the layer. Instead they could be added to a view that in turn uses the layer for its drawing.
Copying layers
During the custom animation, Core Animation is going to want to create and render different layer configurations for different frames. Unlike most of Apple's other frameworks, this happens using the copy constructor init(layer:). For the above five properties to be copied along, we need to override init(layer:) and copy over their values.
In Swift we also have to override the plain init() and init?(coder).
override init(layer: Any) {
super.init(layer: layer)
guard let other = layer as? PieSegmentLayer else { return }
fillColor = other.fillColor
strokeColor = other.strokeColor
startAngle = other.startAngle
endAngle = other.endAngle
strokeWidth = other.strokeWidth
}
override init() {
super.init()
}
required init?(coder aDecoder: NSCoder) {
return nil
}
Reacting to change
Core Animation is in many ways built for performance. One of the ways it achieves this is by avoiding unnecessary work. By default, a layer won't redraw itself when a property changes. But these properties is used for drawing, and we want the layer to redraw when any of them changes. To do that, we need to override needsDisplay(forKey:) and return true if the key was one of these properties.
override class func needsDisplay(forKey key: String) -> Bool {
switch key {
case #keyPath(startAngle), #keyPath(endAngle),
#keyPath(strokeWidth),
#keyPath(fillColor), #keyPath(strokeColor):
return true
default:
return super.needsDisplay(forKey: key)
}
}
Additionally, If we want the layers default implicit animations for these properties, we need to override action(forKey:) to return a partially configured animation object. If we only want some properties (e.g. the angles) to implicitly animate, then we only need to return an animation for those properties. Unless we need something very custom, it's good to just return a basic animation with the fromValue set to the current presentation value:
override func action(forKey key: String) -> CAAction? {
switch key {
case #keyPath(startAngle), #keyPath(endAngle):
let anim = CABasicAnimation(keyPath: key)
anim.fromValue = presentation()?.value(forKeyPath: key)
return anim
default:
return super.action(forKey: key)
}
}
Drawing
The last piece of a custom animation is the custom drawing. This is done by overriding draw(in:) and using the supplied context to draw the layer:
override func draw(in ctx: CGContext) {
let center = CGPoint(x: bounds.midX, y: bounds.midY)
// subtract half the stroke width to avoid clipping the stroke
let radius = min(center.x, center.y) - strokeWidth / 2
// The two angle properties are in degrees but CG wants them in radians.
let start = startAngle * .pi / 180
let end = endAngle * .pi / 180
ctx.beginPath()
ctx.move(to: center)
ctx.addLine(to: CGPoint(x: center.x + radius * cos(start),
y: center.y + radius * sin(start)))
ctx.addArc(center: center, radius: radius,
startAngle: start, endAngle: end,
clockwise: start > end)
ctx.closePath()
// Configure the graphics context
if let fillCGColor = fillColor?.cgColor {
ctx.setFillColor(fillCGColor)
}
if let strokeCGColor = strokeColor?.cgColor {
ctx.setStrokeColor(strokeCGColor)
}
ctx.setLineWidth(strokeWidth)
ctx.setLineCap(.round)
ctx.setLineJoin(.round)
// Draw
ctx.drawPath(using: .fillStroke)
}
Here I've filled and stroked a pie segment that extends from the center of the layer to the nearest edge. You should replace this with your custom drawing.
A custom animation in action
With all that code in place, we now have a custom layer subclass whose properties can be animated both implicitly (just by changing them) and explicitly (by adding a CAAnimation for their key). The results looks something like this:
Final words
It might not be obvious with the frame rate of those animations but one strong benefit from leveraging Core Animation (in different ways) in both these solutions is that it decouples the drawing of a single state from the timing of an animations.
That means that the layer doesn't know and doesn't have to know about the duration, delays, timing curves, etc. These can all be configured and controlled externally.
So at last I have found a solution. It took me time to understand that there is indeed no way to animate the fill of the shape, but we can trick CA engine by creating a filled circle by making the stroke (i.e. the border of the arc) extremely wide, so that it fills the whole circle!
extension CGFloat {
func toRadians() -> CGFloat {
return self * CGFloat(Double.pi) / 180.0
}
}
import UIKit
class SliceView: UIView {
let circleLayer = CAShapeLayer()
var fromAngle:CGFloat = 30
var toAngle:CGFloat = 150
var color:UIColor = UIColor.magenta
override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
convenience init(frame:CGRect, fromAngle:CGFloat, toAngle:CGFloat, color:UIColor) {
self.init(frame:frame)
self.fromAngle = fromAngle
self.toAngle = toAngle
self.color = color
}
func setup() {
circleLayer.strokeColor = color.cgColor
circleLayer.fillColor = UIColor.clear.cgColor
layer.addSublayer(circleLayer)
layer.backgroundColor = UIColor.brown.cgColor
}
override func layoutSubviews() {
super.layoutSubviews()
let startAngle:CGFloat = (fromAngle-90).toRadians()
let endAngle:CGFloat = (toAngle-90).toRadians()
let center = CGPoint(x: bounds.midX, y: bounds.midY)
let radius = min(bounds.width, bounds.height) / 4
let path = UIBezierPath(arcCenter: CGPoint(x: 0,y :0), radius: radius, startAngle: startAngle, endAngle: endAngle, clockwise: true)
circleLayer.position = center
circleLayer.lineWidth = radius*2
circleLayer.path = path.cgPath
}
public func animate() {
let pathAnimation = CABasicAnimation(keyPath: "strokeEnd")
pathAnimation.duration = 3.0;
pathAnimation.fromValue = 0.0;
pathAnimation.toValue = 1.0;
circleLayer.add(pathAnimation, forKey: "strokeEndAnimation")
}
}
So, now we can add it into our view controller and run the animation. In my case - I'm bridging it into Objecive-C but you can easily adapt it to swift.
I simply can't believe that in 2017 it was still not possible to find a ready solution for this simple task. It took me days to have that done. I really hope it will help others!
Here is how I'm using my class:
#implementation ViewController
{
SliceView *sv_;
}
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = UIColor.grayColor;
CGFloat width = 240.0;
CGFloat height = 160.0;
CGRect r = CGRectMake(
self.view.frame.size.width/2 - width/2,
self.view.frame.size.height/2 - height/2,
width, height);
sv_ = [[SliceView alloc] initWithFrame:r fromAngle:150 toAngle:30 color:[UIColor yellowColor] ];
[self.view addSubview:sv_];
}
- (IBAction)pressedGo:(id)sender {
[sv_ animate];
}
I'm adding a slight improvement for David's class. (David - you are welcome to copy into your book-quality answer!)
You can add the following init function:
convenience init(frame:CGRect, startAngle:CGFloat, endAngle:CGFloat, fillColor:UIColor,
strokeColor:UIColor, strokeWidth:CGFloat) {
self.init()
self.frame = frame
self.startAngle = startAngle
self.endAngle = endAngle
self.fillColor = fillColor
self.strokeColor = strokeColor
self.strokeWidth = strokeWidth
}
and then call it like this (Objective-C in my case):
PieSegmentLayer *sliceLayer = [[PieSegmentLayer alloc] initWithFrame:r startAngle:30 endAngle:180 fillColor:[UIColor cyanColor] strokeColor:[UIColor redColor] strokeWidth:4];
[self.view.layer addSublayer:sliceLayer];
I want to create a custom UIView subclass representing a bunch of stars on a dark-blue sky.
Therefore, I created this view:
import UIKit
class ConstellationView: UIView {
// MARK: - Properties
#IBInspectable var numberOfStars: Int = 80
#IBInspectable var animated: Bool = false
// Private properties
private var starsToDraw = [CAShapeLayer]()
// Layers
private let starsLayer = CAShapeLayer()
// MARK: - Drawing
// override func drawRect(rect: CGRect) {
override func layoutSubviews() {
// Generate stars
drawStars(rect: self.bounds)
}
/// Generate stars
func drawStars(rect: CGRect) {
let width = rect.size.width
let height = rect.size.height
let screenBounds = UIScreen.main.bounds
// Create the stars and store them in starsToDraw array
for _ in 0 ..< numberOfStars {
let x = randomFloat() * width
let y = randomFloat() * height
// Calculate the thinness of the stars as a percentage of the screen resolution
let thin: CGFloat = max(screenBounds.width, screenBounds.height) * 0.003 * randomFloat()
let starLayer = CAShapeLayer()
starLayer.path = UIBezierPath(ovalIn: CGRect(x: x, y: y, width: thin, height: thin)).cgPath
starLayer.fillColor = UIColor.white.cgColor
starsToDraw.append(starLayer)
}
// Define a fade animation
let appearAnimation = CABasicAnimation(keyPath: "opacity")
appearAnimation.fromValue = 0.2
appearAnimation.toValue = 1
appearAnimation.duration = 1
appearAnimation.fillMode = kCAFillModeForwards
// Add the animation to each star (if animated)
for (index, star) in starsToDraw.enumerated() {
if animated {
// Add 1 s between each animation
appearAnimation.beginTime = CACurrentMediaTime() + TimeInterval(index)
star.add(appearAnimation, forKey: nil)
}
starsLayer.insertSublayer(star, at: 0)
}
// Add the stars layer to the view layer
layer.insertSublayer(starsLayer, at: 0)
}
private func randomFloat() -> CGFloat {
return CGFloat(arc4random()) / CGFloat(UINT32_MAX)
}
}
It works quite well, here is the result:
However, I'd like to have it animated, that is, each one of the 80 stars should appear one after the other, with a 1 second delay.
I tried to increase the beginTimeof my animation, but it does not seem to do the trick.
I checked with drawRect or layoutSubviews, but there is no difference.
Could you help me ?
Thanks
PS: to reproduce my app, just create a new single view app in XCode, create a new file with this code, and set the ViewController's view as a ConstellationView, with a dark background color. Also set the animated property to true, either in Interface Builder, or in the code.
PPS: this is in Swift 3, but I think it's still comprehensible :-)
You're really close, only two things to do!
First, you need to specify the key when you add the animation to the layer.
star.add(appearAnimation, forKey: "opacity")
Second, the fill mode for the animation needs to be kCAFillModeBackwards instead of kCAFillModeForwards.
For a more detailed reference see - https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/CoreAnimation_guide/AdvancedAnimationTricks/AdvancedAnimationTricks.html
And here's a fun tutorial (for practice with CAAnimations!) - https://www.raywenderlich.com/102590/how-to-create-a-complex-loading-animation-in-swift
Hope this helps 😀
Full Code:
class ConstellationView: UIView {
// MARK: - Properties
#IBInspectable var numberOfStars: Int = 80
#IBInspectable var animated: Bool = true
// Private properties
private var starsToDraw = [CAShapeLayer]()
// Layers
private let starsLayer = CAShapeLayer()
override func awakeFromNib() {
super.awakeFromNib()
}
// MARK: - Drawing
override func layoutSubviews() {
// Generate stars
drawStars(rect: self.bounds)
}
/// Generate stars
func drawStars(rect: CGRect) {
let width = rect.size.width
let height = rect.size.height
let screenBounds = UIScreen.main.bounds
// Create the stars and store them in starsToDraw array
for _ in 0 ..< numberOfStars {
let x = randomFloat() * width
let y = randomFloat() * height
// Calculate the thinness of the stars as a percentage of the screen resolution
let thin: CGFloat = max(screenBounds.width, screenBounds.height) * 0.003 * randomFloat()
let starLayer = CAShapeLayer()
starLayer.path = UIBezierPath(ovalIn: CGRect(x: x, y: y, width: thin, height: thin)).cgPath
starLayer.fillColor = UIColor.white.cgColor
starsToDraw.append(starLayer)
}
// Define a fade animation
let appearAnimation = CABasicAnimation(keyPath: "opacity")
appearAnimation.fromValue = 0.2
appearAnimation.toValue = 1
appearAnimation.duration = 1
appearAnimation.fillMode = kCAFillModeBackwards
// Add the animation to each star (if animated)
for (index, star) in starsToDraw.enumerated() {
if animated {
// Add 1 s between each animation
appearAnimation.beginTime = CACurrentMediaTime() + TimeInterval(index)
star.add(appearAnimation, forKey: "opacity")
}
starsLayer.insertSublayer(star, above: nil)
}
// Add the stars layer to the view layer
layer.insertSublayer(starsLayer, above: nil)
}
private func randomFloat() -> CGFloat {
return CGFloat(arc4random()) / CGFloat(UINT32_MAX)
}
}
I have a UIView class in my app which plots a line graph. In there, I assign my graphPoints variables like so :
var graphPoints:[Int] = [1,2,3,5,7,9]
var graphPoints2:[Int] = [1,2,3,5,7,9]
What I want to do is pass an array of Int from another class and assign those variables, but I am not sure how to do it. Initially i put all my code into one func with array [Int] as parameters and called it from another class but it stopped plotting the graph altogether. How do i do this?
Here is my UIVIew GraphPlotter class code :
import UIKit
#IBDesignable class GraphPlotter: UIView {
var graphPoints:[Int] = [1,2,3,5,7,9]
var graphPoints2:[Int] = [1,2,3,5,7,9]
//1 - the properties for the gradient
var startColor: UIColor = UIColor.redColor()
var endColor: UIColor = UIColor.greenColor()
override func drawRect(rect: CGRect) {
let width = rect.width
let height = rect.height
//set up background clipping area
let path = UIBezierPath(roundedRect: rect,
byRoundingCorners: UIRectCorner.AllCorners,
cornerRadii: CGSize(width: 8.0, height: 8.0))
path.addClip()
//2 - get the current context
let context = UIGraphicsGetCurrentContext()
let colors = [startColor.CGColor, endColor.CGColor]
//3 - set up the color space
let colorSpace = CGColorSpaceCreateDeviceRGB()
//4 - set up the color stops
let colorLocations:[CGFloat] = [0.0, 1.0]
//5 - create the gradient
let gradient = CGGradientCreateWithColors(colorSpace,
colors,
colorLocations)
//6 - draw the gradient
var startPoint = CGPoint.zero
var endPoint = CGPoint(x:0, y:self.bounds.height)
CGContextDrawLinearGradient(context,
gradient,
startPoint,
endPoint,
[])
//calculate the x point
let margin:CGFloat = 40.0
let columnXPoint = { (column:Int) -> CGFloat in
//Calculate gap between points
let spacer = (width - margin*2 - 4) /
CGFloat((self.graphPoints.count - 1))
var x:CGFloat = CGFloat(column) * spacer
x += margin + 2
return x
}
// calculate the y point
let topBorder:CGFloat = 60
let bottomBorder:CGFloat = 50
let graphHeight = height - topBorder - bottomBorder
let maxValue = graphPoints2.maxElement()!
let columnYPoint = { (graphPoint2:Int) -> CGFloat in
var y:CGFloat = CGFloat(graphPoint2) /
CGFloat(maxValue) * graphHeight
y = graphHeight + topBorder - y // Flip the graph
return y
}
// draw the line graph
UIColor.flatTealColor().setFill()
UIColor.flatTealColor().setStroke()
//set up the points line
let graphPath = UIBezierPath()
//go to start of line
graphPath.moveToPoint(CGPoint(x:columnXPoint(0),
y:columnYPoint(graphPoints2[0])))
//add points for each item in the graphPoints array
//at the correct (x, y) for the point
for i in 1..<graphPoints.count {
let nextPoint = CGPoint(x:columnXPoint(i),
y:columnYPoint(graphPoints2[i]))
graphPath.addLineToPoint(nextPoint)
}
//Create the clipping path for the graph gradient
//1 - save the state of the context (commented out for now)
CGContextSaveGState(context)
//2 - make a copy of the path
let clippingPath = graphPath.copy() as! UIBezierPath
//3 - add lines to the copied path to complete the clip area
clippingPath.addLineToPoint(CGPoint(
x: columnXPoint(graphPoints.count - 1),
y:height))
clippingPath.addLineToPoint(CGPoint(
x:columnXPoint(0),
y:height))
clippingPath.closePath()
//4 - add the clipping path to the context
clippingPath.addClip()
let highestYPoint = columnYPoint(maxValue)
startPoint = CGPoint(x:margin, y: highestYPoint)
endPoint = CGPoint(x:margin, y:self.bounds.height)
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, [])
CGContextRestoreGState(context)
//draw the line on top of the clipped gradient
graphPath.lineWidth = 2.0
graphPath.stroke()
//Draw the circles on top of graph stroke
for i in 0..<graphPoints.count {
var point = CGPoint(x:columnXPoint(i), y:columnYPoint(graphPoints2[i]))
point.x -= 5.0/2
point.y -= 5.0/2
let circle = UIBezierPath(ovalInRect:
CGRect(origin: point,
size: CGSize(width: 5.0, height: 5.0)))
circle.fill()
let label = UILabel(frame: CGRectMake(0, 0, 200, 21))
label.center = CGPointMake(160, 284)
label.textAlignment = NSTextAlignment.Center
// label.text = "I'am a test label"
self.addSubview(label)
}
//Draw horizontal graph lines on the top of everything
let linePath = UIBezierPath()
//top line
linePath.moveToPoint(CGPoint(x:margin, y: topBorder))
linePath.addLineToPoint(CGPoint(x: width - margin,
y:topBorder))
//center line
linePath.moveToPoint(CGPoint(x:margin,
y: graphHeight/2 + topBorder))
linePath.addLineToPoint(CGPoint(x:width - margin,
y:graphHeight/2 + topBorder))
//bottom line
linePath.moveToPoint(CGPoint(x:margin,
y:height - bottomBorder))
linePath.addLineToPoint(CGPoint(x:width - margin,
y:height - bottomBorder))
let color = UIColor.flatTealColor()
color.setStroke()
linePath.lineWidth = 1.0
linePath.stroke()
}
}
DBController, func dosmth where I pass the array :
func dosmth(metadata: DBMetadata!) {
let documentsDirectoryPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0]
let localFilePath = (documentsDirectoryPath as NSString).stringByAppendingPathComponent(metadata.filename)
var newarray = [Int]()
do{
let data = try String(contentsOfFile: localFilePath as String,
encoding: NSASCIIStringEncoding)
print(data)
newarray = data.characters.split(){$0 == ","}.map{
Int(String.init($0).stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet()))!}
print(newarray)
}
catch let error { print(error) }
//Probably wrong
GraphPlotter().graphPoints = newarray
GraphPlotter().graphPoints2 = newarray
}
So your drawRect method is based on the two variables graphPoints and graphPoints2. Create a method whose job is to update the arrays of these two variables, and then invoke setNeedsDisplay - which will go on to redraw the view.
func plotGraphPoints(gpArray1 : [Int], andMorePoints gpArray2: [Int] ) {
print("Old Values", self.graphPoints)
self.graphPoints = gpArray1
self.graphPoints2 = gpArray2
print("New values", self.graphPoints)
self.setNeedsDisplay()
}
First, I'd set these up so that any update will redraw the view:
var graphPoints:[Int]? { didSet { setNeedsDisplay() } }
var graphPoints2:[Int]? { didSet { setNeedsDisplay() } }
Note, I made those optionals, because you generally want it to handle the absence of data with nil values rather than dummy values. This does assume, though, that you'll tweak your implementation to detect and handle these nil values, e.g., before you start drawing the lines, do a
guard graphPoints != nil && graphPoints2 != nil else { return }
But, I notice that this whole class is IBDesignable, in which case, you probably want a prepareForInterfaceBuilder that provides sample data:
override func prepareForInterfaceBuilder() {
super.prepareForInterfaceBuilder()
graphPoints = [1,2,3,5,7,9]
graphPoints2 = [1,2,3,5,7,9]
}
Second, your other class needs to have a reference to this custom view.
If this "other" class is the view controller and you added the custom view via IB, you would just add a #IBOutlet for the custom view to this view controller. If you added this custom view programmatically, you'd just keep a reference to it in some property after adding it to the view hierarchy. But, however you added a reference to that view, say graphView, you'd just set these properties:
graphView.graphPoints = ...
graphView.graphPoints2 = ...
If this "other" class is something other than a view controller (and in discussion, it sounds like the class in question is a controller for processing of asynchronous DropBox API), you also need to give that class some mechanism to reference the view controller (and thus the custom view). You can accomplish this by either implementing a "completion handler pattern" or a "delegate-protocol" pattern.