Presentr is a simple wrapper for the Custom View Controller Presentation API introduced in iOS 8.
It is very common in an app to want to modally present a view on top of the current screen without covering it completely. It can be for presenting an alert, a menu, or any kind of popup with some other functionality.
Before iOS 8 this was done by adding a subiew on top of your content, but that is not the recommended way since a modal should ideally have its own view controller for handling all of the logic. View controller containment was also used, and was a better alternative, but still not ideal for this use case.
iOS 8 fixed all of this by introducing Custom View Controller Presentations, which allowed us to modally present view controllers in new ways. But in order to use this API it is up to us to implement a couple of classes and delegates that could be confusing for some.
Presentr is made to simplify this process by hiding all of that and providing a couple of custom presentations and transitions that I think you will find useful. If you want to contribute and add more presentations or transitions please send me a pull request!
use_frameworks!
pod 'Presentr'
- Download and drop
/Presentr
folder in your project. - Congratulations!
public enum PresentationType {
case Alert
case Popup
case TopHalf
case BottomHalf
case Custom(width: ModalSize, height: ModalSize, center: ModalCenterPosition)
}
public enum TransitionType{
// System provided
case CoverVertical
case CrossDissolve
case FlipHorizontal
// Custom
case CoverVerticalFromTop
case CoverHorizontalFromRight
case CoverHorizontalFromLeft
}
It is important to hold on to the Presentr object as a property on the presenting/current View Controller since internally it will be used as a delegate for the custom presentation, so you must hold a strong reference to it.
class ViewController: UIViewController{
let presenter: Presentr = {
let presenter = Presentr(presentationType: .Alert)
presenter.transitionType = .CoverHorizontalFromRight // Optional
return presenter
}()
}
Both types can be changed later on in order to reuse the Presentr object for other presentations.
presenter.presentationType = .Popup
presenter.transitionType = .CoverVerticalFromTop
Now you can also choose to disable rounded corners on the view controller that will be presented. Default is true except for .TopHalf and .BottomHalf presentation types.
presenter.roundCorners = false
Instantiate the View Controller you want to present. Remember to setup autolayout on it so it can be displayed well on any size.
let controller = SomeViewController()
customPresentViewController(presenter, viewController: controller, animated: true, completion: nil)
This is a helper method provided for you as an extension on UIViewController. It handles setting the Presentr object as the delegate for the presentation & transition.
If you need to present a controller in a way that is not handled by the 4 included presentation types you can create your own. You create a custom PresentationType using the .Custom case on the PresentationType enum.
let customType = PresentationType.Custom(width: width, height: height, center: center)
It has three associated values for the width, height and center position of the presented controller. For setting them we use two other enums.
// This is used to calculate either a width or height value.
public enum ModalSize {
case Default
case Half
case Full
case Custom(size: Float)
}
// This is used to calculate the center point position for the modal.
public enum ModalCenterPosition {
case Center
case TopCenter
case BottomCenter
case Custom(centerPoint: CGPoint) // Custom fixed center point.
case CustomOrigin(origin: CGPoint) // Custom fixed origin point.
}
This allows us to use a fixed value when we want
let width = ModalSize.Custom(size: 300) // Custom 300pt width
But also let Presentr handle the calculations when we want something more common.
let height = ModalSize.Full // Whole screen height
We could also set a fixed position
let position = ModalCenterPosition.Custom(centerPoint: CGPoint(x: 150, y: 150)) // Custom center point
Or let presentr calculate the position
let position = ModalCenterPosition.Center // Center of the screen
So we can mix and match, and have the benefit of a custom PresentationType but still have Presentr calculating the values we don't want to do ourselves. The following code creates a Presentr object with a custom PresentationType which shows the alert in a small top banner.
class ViewController: UIViewController{
let customPresenter: Presentr = {
let width = ModalSize.Full
let height = ModalSize.Custom(size: 150)
let center = ModalCenterPosition.CustomOrigin(origin: CGPoint(x: 0, y: 0))
let customType = PresentationType.Custom(width: width, height: height, center: center)
let customPresenter = Presentr(presentationType: customType)
customPresenter.transitionType = .CoverVerticalFromTop
customPresenter.roundCorners = false
return customPresenter
}()
}
Presentr also comes with a cool AlertViewController baked in if you want something different from Apple's. The API is very similar to Apple's alert controller.
let title = "Are you sure?"
let body = "There is no way to go back after you do this!"
let controller = Presentr.alertViewController(title: title, body: body)
let deleteAction = AlertAction(title: "Sure ๐ถ", style: .Destructive) {
print("Deleted!")
}
let okAction = AlertAction(title: "NO, sorry ๐", style: .Cancel){
print("Ok!")
}
controller.addAction(deleteAction)
controller.addAction(okAction)
presenter.presentationType = .Alert
customPresentViewController(presenter, viewController: controller, animated: true, completion: nil)
- Xcode 7.3+
- iOS 8.0+
- Swift 2.2+
Read the docs. Generated with jazzy.
- Add more presentation types
- Add more transition types (animations)
- Add other baked in View Controller's for common uses (like the AlertViewController)
- Add Testing
Daniel Lozano
iOS Developer @ Icalia Labs
Logo design by Eduardo Higareda
Alert design by Noe Araujo
Presentr is released under the MIT license.
See LICENSE for details.