Labeled Picker View In Swift

LabeledPickerView.swift

//
//  LabeledPickerView.swift
//  Created by Kristopher Jackson
//

import UIKit

protocol LabeledPickerViewDataSource {
    func numberOfComponents(in pickerView: UIPickerView) -> Int
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
}

protocol LabeledPickerViewDelegate {
    func pickerView(_ pickerView: UIPickerView, labelForComponent component: Int) -> String?
    func pickerView(_ pickerView: UIPickerView, textAlignmentForComponent component: Int) -> NSTextAlignment?
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String?
}

class LabeledPickerView: UIView {
    
    var delegate: LabeledPickerViewDelegate?
    var dataSource: LabeledPickerViewDataSource?
    var pickerView: UIPickerView = UIPickerView()
    
    var labelFont: UIFont = .boldSystemFont(ofSize: 18)
    var font: UIFont = .systemFont(ofSize: 20, weight: .regular)
    
    var textEdgeInsets: UIEdgeInsets {
        get {
            return self.insets
        }
        set {
            self.insets = newValue
        }
    }
    
    private var labels: [UILabel] = []
    private var insets: UIEdgeInsets = .zero
    private var labelWidthAnchors: [NSLayoutConstraint] = []
    
    init() {
        super.init(frame: .zero)
        self.setView()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.setView()
    }
    
    private func setView() {
        
        self.backgroundColor = .clear
        
        self.pickerView.delegate = self
        self.pickerView.dataSource = self
        
        self.addSubview(self.pickerView)
        NSLayoutConstraint.activate([
            self.pickerView.widthAnchor.constraint(equalTo: self.widthAnchor),
            self.pickerView.heightAnchor.constraint(equalTo: self.heightAnchor),
            self.pickerView.centerXAnchor.constraint(equalTo: self.centerXAnchor),
            self.pickerView.centerYAnchor.constraint(equalTo: self.centerYAnchor),
        ])
        
    }
    
    private func setLabels() {
        
        for component in 0..<self.pickerView.numberOfComponents {
        
            /// Skip iteration if label was created
            if self.labels.indices.contains(component) { continue }
            
            /// Create label
            let label: Label = Label()
            label.font = self.labelFont
            label.textAlignment = .right
            label.paddingTop = self.insets.top
            label.paddingLeft = self.insets.left
            label.paddingRight = self.insets.right
            label.paddingBottom = self.insets.bottom
            label.translatesAutoresizingMaskIntoConstraints = false
            label.text = self.delegate?.pickerView(self.pickerView, labelForComponent: component)
            
            /// Add label to picker view
            self.pickerView.addSubview(label)
            self.labelWidthAnchors.append(label.widthAnchor.constraint(equalToConstant: 0))
            
            NSLayoutConstraint.activate([
                self.labelWidthAnchors[self.labelWidthAnchors.count - 1],
                label.centerYAnchor.constraint(equalTo: self.pickerView.centerYAnchor),
                self.labels.count == 0 ? (label.leftAnchor.constraint(equalTo: self.pickerView.leftAnchor))
                    : (label.leftAnchor.constraint(equalTo: self.labels[component - 1].rightAnchor, constant: 5)),
            ])
        
            self.labels.append(label)
            
        }
    }
    
}

extension LabeledPickerView: UIPickerViewDataSource {
    
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return self.dataSource?.numberOfComponents(in: pickerView) ?? 1
    }
    
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return self.dataSource?.pickerView(pickerView, numberOfRowsInComponent: component) ?? 0
    }
    
}

extension LabeledPickerView: UIPickerViewDelegate {
    
    func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
        
        self.setLabels()
        
        var attributedString: NSMutableAttributedString!
        let labelString: String? = self.labels[component].text
        let titleString: String = self.delegate?.pickerView(pickerView, titleForRow: row, forComponent: component) ?? ""
        
        var pickerLabel: Label?
        if (view as? UILabel) == nil {
            pickerLabel = Label()
            pickerLabel?.font = self.font
            pickerLabel?.textAlignment = .right
            pickerLabel?.paddingTop = self.insets.top
            pickerLabel?.paddingLeft = self.insets.left
            pickerLabel?.paddingRight = self.insets.right
            pickerLabel?.paddingBottom = self.insets.bottom
        }
        
        if let label = labelString {
            
            let string = "\(titleString) \(label)"
            attributedString = NSMutableAttributedString(string: string)
            
            attributedString.addAttributes([
                .font : self.labelFont,
                .foregroundColor : UIColor.clear,
            ], range: NSRange(location: string.count - label.count, length: label.count))
            
        } else {
            
            attributedString = NSMutableAttributedString(string: titleString)
            pickerLabel?.textAlignment = self.delegate?.pickerView(pickerView, textAlignmentForComponent: component) ?? .center
            
        }
        
        pickerLabel?.attributedText = attributedString
        self.labelWidthAnchors[component].constant = pickerView.rowSize(forComponent: component).width

        return pickerLabel!
        
    }
    
}

@IBDesignable
class Label: UILabel {
    
    var textEdgeInsets = UIEdgeInsets.zero {
        didSet { invalidateIntrinsicContentSize() }
    }
    
    open override func textRect(forBounds bounds: CGRect, limitedToNumberOfLines numberOfLines: Int) -> CGRect {
        let insetRect = bounds.inset(by: textEdgeInsets)
        let textRect = super.textRect(forBounds: insetRect, limitedToNumberOfLines: numberOfLines)
        let invertedInsets = UIEdgeInsets(top: -textEdgeInsets.top,
                                          left: -textEdgeInsets.left,
                                          bottom: -textEdgeInsets.bottom,
                                          right: -textEdgeInsets.right)
        return textRect.inset(by: invertedInsets)
    }
    
    override func drawText(in rect: CGRect) {
        super.drawText(in: rect.inset(by: textEdgeInsets))
    }
    
    @IBInspectable
    var paddingLeft: CGFloat {
        set { textEdgeInsets.left = newValue }
        get { return textEdgeInsets.left }
    }
    
    @IBInspectable
    var paddingRight: CGFloat {
        set { textEdgeInsets.right = newValue }
        get { return textEdgeInsets.right }
    }
    
    @IBInspectable
    var paddingTop: CGFloat {
        set { textEdgeInsets.top = newValue }
        get { return textEdgeInsets.top }
    }
    
    @IBInspectable
    var paddingBottom: CGFloat {
        set { textEdgeInsets.bottom = newValue }
        get { return textEdgeInsets.bottom }
    }
    
}