AdaptiveCode/AdaptiveCode/RatingControl.swift
/* |
Copyright (C) 2016 Apple Inc. All Rights Reserved. |
See LICENSE.txt for this sample’s licensing information |
Abstract: |
A control that allows viewing and editing a rating. |
*/ |
import UIKit |
class RatingControl: UIControl { |
/* |
NOTE: Unlike OverlayView, this control does not implement `intrinsicContentSize()`. |
Instead, this control configures its auto layout constraints such that the |
size of the star images that compose it can be used by the layout engine |
to derive the desired content size of this control. Since UIImageView will |
automatically load the correct UIImage asset for the current trait collection, |
we receive automatic adaptivity support for free just by including the images |
for both the compact and regular size classes. |
*/ |
static let minimumRating = 0 |
static let maximumRating = 4 |
var rating = RatingControl.minimumRating { |
didSet { |
updateImageViews() |
} |
} |
fileprivate let backgroundView = UIVisualEffectView(effect: UIBlurEffect(style: .light)) |
fileprivate var imageViews = [UIImageView]() |
// This initializer will be called if the control is created programatically. |
override init(frame: CGRect) { |
super.init(frame: frame) |
commonInit() |
} |
// This initializer will be called if the control is loaded from a storyboard. |
required init?(coder aDecoder: NSCoder) { |
super.init(coder: aDecoder) |
commonInit() |
} |
// Initialization code common to instances created programmatically as well as instances unarchived from a storyboard. |
fileprivate func commonInit() { |
backgroundView.contentView.backgroundColor = UIColor(white: 0.7, alpha: 0.3) |
addSubview(backgroundView) |
// Create image views for each of the sections that make up the control. |
for rating in RatingControl.minimumRating...RatingControl.maximumRating { |
let imageView = UIImageView() |
imageView.isUserInteractionEnabled = true |
// Set up our image view's images. |
imageView.image = UIImage(named: "ratingInactive") |
imageView.highlightedImage = UIImage(named: "ratingActive") |
let localizedStringFormat = NSLocalizedString("%d stars", comment: "X stars") |
imageView.accessibilityLabel = String.localizedStringWithFormat(localizedStringFormat, rating + 1) |
addSubview(imageView) |
imageViews.append(imageView) |
} |
// Setup constraints. |
var newConstraints = [NSLayoutConstraint]() |
backgroundView.translatesAutoresizingMaskIntoConstraints = false |
let views = ["backgroundView": backgroundView] |
// Keep our background matching our size |
newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "|[backgroundView]|", options: [], metrics: nil, views: views) |
newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|[backgroundView]|", options: [], metrics: nil, views: views) |
// Place the individual image views side-by-side with margins |
var lastImageView: UIImageView? |
for imageView in imageViews { |
imageView.translatesAutoresizingMaskIntoConstraints = false |
let currentImageViews: [String: AnyObject] |
if lastImageView != nil { |
currentImageViews = [ |
"lastImageView": lastImageView!, |
"imageView": imageView |
] |
} |
else { |
currentImageViews = ["imageView": imageView] |
} |
newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|-4-[imageView]-4-|", options: [], metrics: nil, views: currentImageViews) |
newConstraints += [ |
NSLayoutConstraint(item: imageView, attribute: .width, relatedBy: .equal, toItem: imageView, attribute: .height, multiplier: 1, constant: 0) |
] |
if lastImageView != nil { |
newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "[lastImageView][imageView(==lastImageView)]", options: [], metrics: nil, views: currentImageViews) |
} |
else { |
newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "|-4-[imageView]", options: [], metrics: nil, views: currentImageViews) |
} |
lastImageView = imageView |
} |
let currentImageViews = ["lastImageView": lastImageView!] |
newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "[lastImageView]-4-|", options: [], metrics: nil, views: currentImageViews) |
NSLayoutConstraint.activate(newConstraints) |
} |
func updateImageViews() { |
for (index, imageView) in imageViews.enumerated() { |
imageView.isHighlighted = index + RatingControl.minimumRating <= rating |
} |
} |
// MARK: Touches |
func updateRatingWithTouches(_ touches: Set<UITouch>, event: UIEvent?) { |
guard let touch = touches.first else { return } |
let position = touch.location(in: self) |
guard let touchedView = hitTest(position, with: event) as? UIImageView else { return } |
guard let touchedIndex = imageViews.index(of: touchedView) else { return } |
rating = RatingControl.minimumRating + touchedIndex |
sendActions(for: .valueChanged) |
} |
// If you override one of the touch event callbacks, you should override all of them. |
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { |
updateRatingWithTouches(touches, event: event) |
} |
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) { |
updateRatingWithTouches(touches, event: event) |
} |
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) { |
// There's no need to handle `touchesCancelled(_:withEvent:)` for this control. |
} |
override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) { |
// There's no need to handle `touchesCancelled(_:withEvent:)` for this control. |
} |
// MARK: Accessibility |
// This control is not an accessibility element but the individual images that compose it are. |
override var isAccessibilityElement: Bool { |
set { /* ignore value */ } |
get { return false } |
} |
} |
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