CenteredTagCloudView playground code

CenteredTagCloudView.swift

//
//  MultilineLabelCloudView.swift
//
//

import UIKit

/**
Presents a wrapping grid of tokens presented as pills.

Implements sizeThatFits, so it can communicate its
required height to auto layout or other consumers.

*/
class MultilineLabelCloudView: UIView, UICollectionViewDataSource
{
  var pillBackgroundColor:UIColor = UIColor.lightGrayColor()
  var pillTextColor:UIColor = UIColor.darkGrayColor()
  var pillTextFontSize:CGFloat = CGFloat(9)
  var horizontalSpacing:CGFloat = CGFloat(8)
  
  var tokens:[String] = [] { didSet {
    self.collectionView.reloadData()
    self.collectionView.collectionViewLayout.invalidateLayout()
    self.setNeedsLayout()
    self.layoutIfNeeded()
    } }
  
  private weak var collectionView:UICollectionView!
  
  override init(frame: CGRect) {
    super.init(frame: frame)
    self.setup()
  }
  
  required  init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    self.setup()
  }
  
  private func setup() {
    self.backgroundColor = UIColor.clearColor()
    let layout =  CenteredFlowLayout()
    layout.minimumInteritemSpacing = self.horizontalSpacing
    let cv = UICollectionView(frame: self.bounds, collectionViewLayout: layout)
    cv.registerClass(LabelViewCell.self, forCellWithReuseIdentifier: "LabelViewCellIdentifier")
    cv.dataSource = self
    layout.estimatedItemSize = CGSize(width: 60, height: 60)
    cv.backgroundColor = self.backgroundColor
    self.addSubview(cv)
    fillSuperview(cv)
    self.collectionView = cv
  }
  
  /// Returns the size that would present all its content
  override func sizeThatFits(size: CGSize) -> CGSize {
    return self.collectionView.contentSize
  }
  
  // MARK: UICollectionViewDataSource
  
  func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    return 1
  }
  
  func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return tokens.count
  }
  
  // The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
  func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("LabelViewCellIdentifier", forIndexPath: indexPath) as! LabelViewCell
    cell.labelView.label.text = self.tokens[indexPath.row]
    cell.labelView.labelBackgroundColor = pillBackgroundColor
    cell.labelView.label.font = UIFont.systemFontOfSize(self.pillTextFontSize)
    cell.labelView.label.textColor = self.pillTextColor
    return cell
  }
}

class CenteredFlowLayout : UICollectionViewFlowLayout
{
  override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes! {
    let modifiedLayoutAttributes = self.layoutAttributesForElementsInRect(CGRectInfinite)
    // TODO: re-implement for better perf
    if let desiredLayAttr = modifiedLayoutAttributes?.filter({ indexPath.isEqual($0.indexPath) }).first as? UICollectionViewLayoutAttributes {
      return desiredLayAttr
    }
    else
    {
      NSLog("error")
      return super.layoutAttributesForItemAtIndexPath(indexPath)
    }
  }
  
  func modifiedLayoutAttribuets(attributes:[UICollectionViewLayoutAttributes]) -> [UICollectionViewLayoutAttributes]
  {
    return attributes
  }
  
  override func layoutAttributesForElementsInRect(rect: CGRect) -> [AnyObject]?
  {
    typealias Row = [UICollectionViewLayoutAttributes]
    let superAttributes = super.layoutAttributesForElementsInRect(rect) as! [UICollectionViewLayoutAttributes]
    
    // partition the objs into rows
    func inRow(lay1:UICollectionViewLayoutAttributes, row:Row) -> Bool {
      let sameRowEpsilon:CGFloat = 1
      if let lay2 = row.first {
        let absDistance  = fabs(CGRectGetMidY(lay1.frame) - CGRectGetMidY(lay2.frame))
        return (absDistance < sameRowEpsilon)
      }
      return false
    }
    
    func consumeItem(var result:[Row], item:UICollectionViewLayoutAttributes) ->  [Row]
    {
      for (index,row) in enumerate(result) {
        if inRow(item,row) {
          result[index].append(item)
          return result
        }
      }
      // assert: did not match any existing rows
      result.append([item])
      return result
    }
    
    let rowCollections = reduce(superAttributes, [], consumeItem)
    
    // update the layout one row at a time
    
    let collectionViewWidth = CGRectGetWidth(self.collectionView!.bounds)
    for items in rowCollections {
      let itemsInRow = items.count
      let aggregateInterItemSpacing = self.minimumInteritemSpacing * CGFloat(itemsInRow - 1)
      let aggregateItemWidth = items.map({CGRectGetWidth($0.frame)}).reduce(0, combine: +)
      let alignmentWidth = aggregateItemWidth + aggregateInterItemSpacing
      let alignmentXOffset = (collectionViewWidth - alignmentWidth) / 2.0
      
      var previousFrame = CGRectZero
      for item in items {
        var itemFrame = item.frame
        if CGRectEqualToRect(previousFrame, CGRectZero) {
          itemFrame.origin.x = alignmentXOffset
        } else {
          itemFrame.origin.x = CGRectGetMaxX(previousFrame) + self.minimumInteritemSpacing
        }
        item.frame = itemFrame
        previousFrame = itemFrame
      }
    }
    
    return superAttributes
  }
}

class LabelViewCell : UICollectionViewCell
{
  private weak var labelView:LabelView!
  
  override init(frame: CGRect) {
    super.init(frame: frame)
    self.backgroundColor = UIColor.clearColor()
    self.contentView.backgroundColor = UIColor.clearColor()
    let label = LabelView(frame: self.bounds)
    self.contentView.addSubview(label)
    fillSuperview(label)
    self.labelView = label
  }
  
  required init(coder aDecoder:NSCoder) {
    super.init(coder:aDecoder)
    assertionFailure("unimplemented NSCoding initializer")
  }
}

/** Draws a light gray pill-shaped view with an inset label showing dark gray text

Defines its own preferred size via auto layout.

*/
class LabelView: UIView
{
  var labelBackgroundColor:UIColor? {
    get { return self.backgroundColor }
    set {
      self.backgroundColor = newValue
      self.label.backgroundColor = newValue
    }
  }
  
  let label = UILabel(frame: CGRectZero)
  let insetting = UIEdgeInsetsMake(5, 15, 5, 15)
  
  override convenience init(frame:CGRect) {
    // defaults
    let kpillBackgroundColor:UIColor = UIColor.greenColor()
    let kpillTextColor:UIColor = UIColor.whiteColor()
    let kpillTextFontSize:CGFloat = CGFloat(9)
    let kpillTextFont:UIFont = UIFont.systemFontOfSize(kpillTextFontSize)
    
    self.init(frame:frame, pillBackgroundColor:kpillBackgroundColor,pillTextColor:kpillTextColor,pillTextFont:kpillTextFont)
  }
  
  init(frame:CGRect, pillBackgroundColor:UIColor,pillTextColor:UIColor,pillTextFont:UIFont) {
    
    super.init(frame:frame)
    
    self.setTranslatesAutoresizingMaskIntoConstraints(false)
    self.autoresizingMask = UIViewAutoresizing.None
    
    self.backgroundColor = pillBackgroundColor
    self.clipsToBounds = true
    label.backgroundColor = pillBackgroundColor
    label.textColor = pillTextColor
    label.font = pillTextFont
    label.frame = UIEdgeInsetsInsetRect(self.bounds, self.insetting)
    self.addSubview(label)
    
    let views = ["label":label]
    self.label.setTranslatesAutoresizingMaskIntoConstraints(false)
    self.layoutMargins = insetting
    ["V:|-[label]-|","H:|-[label]-|"].map( { (vfl:String) -> String in
      self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat(vfl, options: .allZeros, metrics: nil, views: views))
      return vfl
    })
  }
  
  required init(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
  
  override func layoutSubviews() {
    super.layoutSubviews()
    self.label.frame = UIEdgeInsetsInsetRect(self.bounds,self.insetting)
    self.layer.cornerRadius = self.layer.bounds.size.height / 2.0
  }
  
}


func fillSuperview(view:UIView)
{
  if let superview = view.superview {
    view.setTranslatesAutoresizingMaskIntoConstraints(false)
    view.frame = superview.bounds
    superview.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[v]|", options: NSLayoutFormatOptions.allZeros, metrics: nil, views: ["v":view]))
    superview.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[v]|", options: NSLayoutFormatOptions.allZeros, metrics: nil, views: ["v":view]))
  }
}


let cloudView = MultilineLabelCloudView(frame: CGRect(x: 0, y: 0, width: 310, height: 50))
cloudView.tokens = ["phonenumber","ssn","card","mytoken","word","another word"]
cloudView.backgroundColor = UIColor.yellowColor()
cloudView