Ambience: Minimalist, lightweight brightness adjustment framework library and customizable view components

You may also follow the Ambience tutorial on on Design+Code.

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Ambience is available through CocoaPods and it’s highly recommended you use it. To install it, simply add the following line to your Podfile:

pod 'Ambience'Copy the code

To enable it you have to call the Ambience singleton on your App Delegate like this:

import UIKit
import Ambience

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        _ = Ambience.shared

        return true
    }
}Copy the code

Pretty standard stuff, right?

Ambience is so very convenient because it does a little bit of black magic under the hood. If you feel curious about how this work, scroll down to the Nitty-Gritty section.

To customize an Interface Builder view, use the Inspectable Properties on the Attributes Inspector. Don’t forget to turn Ambience On for that view.

Search, Navigation, and Tab need to be turned on but their respective styles are not customizable.

In this example, we are implementing the current behavior for Search, Navigation and Tab bars. It guards the notification data for the current state as an Ambience State and sets the bar style accordingly.

public override func ambience(_ notification : Notification) { super.ambience(notification) guard let currentState = notification.userInfo? ["currentState"] as? AmbienceState else { return } barStyle = currentState == .invert ? .black : .default }Copy the code

The notification user info dictionary also comes with the previous state so that more complex stateful behaviors can be implemented. It may also come with an animated boolean attribute the is usually set to true and, at the first run, set to false so as not to have animation upon view appearance.

Yes. You need only a line of code to have Ambience work right out of the box. But there is a detail. For this to work, Awake From Nib is swizzled when you call Ambience.shared.

If you don’t know what swizzling is, here goes a little explanation.

Swizzling two methods is nothing but swapping two method addresses. What do I mean by address? Why did I do this?

I wanted every UIView to have access to Ambience. To have that, I had to do some configuration in the UIView before it reaches the device’s screen. I chose to do this in the Awake From Nib method because it’s guaranteed to be called right before the view hits the screen and on most of the UIView objects, such as Navigation Bar, Search Bar and Tab Bar, that have a different lifecycle from a regular UIView.

static let classInit : Void = { swizzling(forClass: UIView.self, originalSelector: #selector(awakeFromNib), swizzledSelector: #selector(swizzled_awakeFromNib)) }() @objc open func swizzled_awakeFromNib () { let name = String(describing:type(of: self)) guard ! NSObject.forbiddenNames.contains(name) else { return } swizzled_awakeFromNib() if ambience { _ = notificationManager } }Copy the code

The swizzling is going to happen to the address of Awake From Nib but will not affect inner calls. Let me explain. When UI Kit calls awakeFromNib on a UIView, what is actually going to happen is view.swizzled_awakeFromNib. Nonetheless, when swizzled_awakeFromNib is called inside swizzled_awakeFromNib, it actually calls awakeFromNib, thus, giving us access to the default implementation.

In another word, this is a complicated way of adding this few lines to every single UIView and any of its children:

if ambience {
    _ = notificationManager
}Copy the code