Extended UITextView with Placeholder

TextViewWithPlaceholder.swift

//
//  TextViewWithPlaceholder.swift
//
//  Created by Bruno Pinheiro on 13/09/17.
//  Copyright © 2017 Bruno Pinheiro. All rights reserved.
//

import UIKit

@IBDesignable
class TextViewWithPlaceholder: UITextView {
  let placeholder: UITextView

  @IBInspectable var placeholderTextColor: UIColor = UIColor.lightGray {
    didSet {
      placeholder.textColor = placeholderTextColor
    }
  }

  @IBInspectable var placeholderText: String = "" {
    didSet {
      placeholder.text = placeholderText
    }
  }

  required init?(coder aDecoder: NSCoder) {
    self.placeholder = UITextView(frame: CGRect.zero)
    super.init(coder: aDecoder)
    setup()
  }

  override init(frame: CGRect, textContainer: NSTextContainer?) {
    self.placeholder = UITextView(frame: frame)
    super.init(frame: frame, textContainer: nil)

    setup()
  }

  private func setup() {
    layoutMargins = UIEdgeInsets()
    configurePlaceholder()
    setNeedsUpdateConstraints()
  }

  private func configurePlaceholder() {
    placeholder.isEditable = false
    placeholder.isUserInteractionEnabled = false
    placeholder.backgroundColor = UIColor.clear
    placeholder.translatesAutoresizingMaskIntoConstraints = false
    addSubview(placeholder)
  }

  override func becomeFirstResponder() -> Bool {
    placeholder.isHidden = true
    return super.becomeFirstResponder()
  }

  override func resignFirstResponder() -> Bool {
    placeholder.isHidden = !text.isEmpty
    return super.resignFirstResponder()
  }

  override func updateConstraints() {
    super.updateConstraints()

    guard !constraintsAlreadySet else {
      return
    }

    constraintsAlreadySet = true
    createPlaceholderConstraints()
  }

  private func createPlaceholderConstraints() {
    placeholder.centerXAnchor.constraint(equalTo: layoutMarginsGuide.centerXAnchor).isActive = true
    placeholder.centerYAnchor.constraint(equalTo: layoutMarginsGuide.centerYAnchor).isActive = true
    placeholder.widthAnchor.constraint(equalTo: layoutMarginsGuide.widthAnchor).isActive = true
    placeholder.heightAnchor.constraint(equalTo: layoutMarginsGuide.heightAnchor).isActive = true
  }

  private var constraintsAlreadySet = false
}

TextViewWithPlaceholderTests.swift

//
//  TextViewWithPlaceholderTests.swift
//
//  Created by Bruno Pinheiro on 13/09/17.
//  Copyright © 2017 Bruno Pinheiro. All rights reserved.
//

import XCTest

@testable import ExtendedTextView

class TextViewWithPlaceholderTests: XCTestCase {
  override func setUp() {
    super.setUp()

    textView = TextViewWithPlaceholder(frame: CGRect.zero)
    _ = textView.becomeFirstResponder()
  }

  func testWhenIsEmptyPlaceholderShouldNotBeHidden() {
    textView.text = ""
    _ = textView.resignFirstResponder()
    XCTAssertFalse(textView.placeholder.isHidden)
  }

  func testWhenContainsTextPlaceholderShouldBeHidden() {
    textView.text = "Hello World!"
    _ = textView.resignFirstResponder()
    XCTAssertTrue(textView.placeholder.isHidden)
  }

  func testPlaceholderColorShouldChangePlaceholderTextColor() {
    textView.placeholderTextColor = UIColor.green
    XCTAssertEqual(textView.placeholder.textColor, UIColor.green)
  }

  func testPlaceholderTextShouldChangePlaceholderText() {
    textView.placeholderText = "Hello!"
    XCTAssertEqual(textView.placeholder.text, "Hello!")
  }

  private var textView: TextViewWithPlaceholder!
}