tmp.swift

import UIKit

import SnapKit

private let insets = UIEdgeInsets(top: 15, left: 10, bottom: 15, right: 10)
private let labelSpacing: CGFloat = 7
private let formPadding: CGFloat = 10

class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource,
UICollectionViewDelegateFlowLayout {
	
	static let itemsPerRow = 5
	static let padding: CGFloat = 4
	
	private let collectionView: UICollectionView
	private let layout = UICollectionViewFlowLayout()
	
	init() {
		layout.scrollDirection = .vertical
		self.collectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
		super.init(nibName: nil, bundle: nil)
	}
	
	required init?(coder aDecoder: NSCoder) {
		layout.scrollDirection = .vertical
		self.collectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
		super.init(coder: aDecoder)
	}
	
	override func viewDidLoad() {
		super.viewDidLoad()
		
		view.backgroundColor = .lightGray
		
		let scrollView = UIScrollView()
		view.addSubview(scrollView)
		scrollView.backgroundColor = .clear
		scrollView.snp.makeConstraints { make in
			make.edges.equalTo(view)
		}
		let contentView = UIView()
		scrollView.addSubview(contentView)
		contentView.backgroundColor = .clear
		contentView.snp.makeConstraints { make in
			make.edges.equalTo(scrollView)
			make.width.equalTo(view)
		}
		
		let nameLabel = UILabel()
		nameLabel.text = "Choose a name"
		nameLabel.numberOfLines = 0
		
		contentView.addSubview(nameLabel)
		nameLabel.snp.makeConstraints { make in
			make.top.left.right.equalTo(contentView)
		}
		
		let nameField = UITextField()
		contentView.addSubview(nameField)
		nameField.snp.makeConstraints { make in
			make.top.equalTo(nameLabel.snp.bottom).offset(labelSpacing)
			make.left.right.equalTo(contentView)
		}
		
		let nameFieldLine = UIView()
		contentView.addSubview(nameFieldLine)
		nameFieldLine.backgroundColor = UIColor.darkGray
		nameFieldLine.snp.makeConstraints { make in
			make.top.equalTo(nameField.snp.bottom)
			make.left.right.equalTo(nameField)
			make.height.equalTo(2)
		}
		
		let descriptionLabel = UILabel()
		contentView.addSubview(descriptionLabel)
		descriptionLabel.text = "Write a description"
		descriptionLabel.numberOfLines = 0
		descriptionLabel.snp.makeConstraints { make in
			make.top.equalTo(nameFieldLine.snp.bottom).offset(formPadding)
			make.left.right.equalTo(contentView)
		}
		
		let descriptionField = UITextView()
		descriptionField.isScrollEnabled = false
		contentView.addSubview(descriptionField)
		descriptionField.textContainer.maximumNumberOfLines = 4
		descriptionField.snp.makeConstraints { make in
			make.top.equalTo(descriptionLabel.snp.bottom).offset(labelSpacing)
			make.left.right.equalTo(contentView)
			make.height.equalTo(descriptionField)
		}
		
		let isPublicLabel = UILabel()
		contentView.addSubview(isPublicLabel)
		isPublicLabel.numberOfLines = 0
		isPublicLabel.snp.makeConstraints { make in
			make.top.equalTo(descriptionField.snp.bottom).offset(formPadding)
			make.left.right.equalTo(contentView)
		}
		
		let isPublicToggle = UISwitch()
		contentView.addSubview(isPublicToggle)
		isPublicToggle.isOn = true
		isPublicToggle.snp.makeConstraints { make in
			make.top.equalTo(isPublicLabel.snp.bottom).offset(10)
			make.right.equalTo(contentView)
		}
		
		let isPublicInfoLabel = UILabel()
		contentView.addSubview(isPublicInfoLabel)
		isPublicInfoLabel.text = "Make it public"
		isPublicInfoLabel.numberOfLines = 0
		isPublicInfoLabel.snp.makeConstraints { make in
			make.top.equalTo(isPublicLabel.snp.bottom).offset(10)
			make.left.equalTo(contentView)
			make.right.equalTo(isPublicToggle.snp.left).offset(-8)
		}
		
		let selectLabel = UILabel()
		contentView.addSubview(selectLabel)
		selectLabel.text = "Select a thing:"
		selectLabel.numberOfLines = 0
		selectLabel.snp.makeConstraints { make in
			make.top.equalTo(isPublicInfoLabel.snp.bottom).offset(formPadding)
			make.right.left.equalTo(contentView)
		}
		
		collectionView.dataSource = self
		collectionView.delegate = self
		
		collectionView.register(UICollectionViewCell.self,
		                        forCellWithReuseIdentifier: "cell")
		
		collectionView.isScrollEnabled = false
		
		collectionView.backgroundColor = .blue
		contentView.addSubview(collectionView)
		collectionView.snp.makeConstraints { make in
			// Probably OK
			make.top.equalTo(selectLabel.snp.bottom).offset(labelSpacing)
			make.left.right.equalTo(contentView)
			
			// set height equal to 0 just so it exists...
			make.height.equalTo(0)
			
			make.bottom.equalTo(scrollView)
		}
		
		// force collectionView to "calculate" itself before view is shown
		// this way, collectionView.contentSize will be valid when we hit viewWillAppear
		collectionView.setNeedsLayout()
		collectionView.layoutIfNeeded()
	}
	
	
	override func viewWillAppear(_ animated: Bool) {
		super.viewWillAppear(animated)
		
		let h = collectionView.contentSize.height
		collectionView.snp.updateConstraints { (make) -> Void in
			make.height.equalTo(h);
		}
	}
	
	// MARK: CollectionView
	func numberOfSections(in collectionView: UICollectionView) -> Int {
		return 1
	}
	
	func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
		return 40
	}
	
	
	func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
		let itemsPerRow = ViewController.itemsPerRow
		let padding = ViewController.padding
		let totalPaddingPerRow = CGFloat(itemsPerRow - 1) * padding + insets.left + insets.right
		let width = (collectionView.bounds.width - totalPaddingPerRow) / CGFloat(ViewController.itemsPerRow)
		return CGSize(width: width, height: width)
	}
	
	
	
	func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
		let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
		//        cell.itemID = 1
		cell.contentView.backgroundColor = UIColor.red
		return cell
	}
}