Building a circular facepile of profile pictures in Swift: how to have the last photo tucked under the first? - ios

Question

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)
}
}

Answer 1

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)