FocusTextView.swift

// TextView subclass that replicates TVOS movies app 
// Also made a quick presentation controller
// Just connect the delegate to the ViewController in IB
// and set the TextView class to FocusTextView

import UIKit

class TextPresentationViewController:UIViewController {
    let label = UILabel()
    let blurStyle = UIBlurEffectStyle.Dark
    
    override func viewDidLoad() {
        
        let blurEffect = UIBlurEffect(style: blurStyle)
        let blurEffectView = UIVisualEffectView(effect: blurEffect)
        blurEffectView.frame = view.bounds
        view.addSubview(blurEffectView)
        
        let vibrancyEffect = UIVibrancyEffect(forBlurEffect: blurEffect)
        let vibrancyEffectView = UIVisualEffectView(effect: vibrancyEffect)
        view.addSubview(vibrancyEffectView)
        
        vibrancyEffectView.addSubview(label)
        
        label.numberOfLines = 0
        label.translatesAutoresizingMaskIntoConstraints = false
        
        view.addConstraints([
            NSLayoutConstraint(item: label, attribute: .Width, relatedBy: .Equal, toItem: view, attribute: .Width, multiplier: 0.5, constant: 0),
            NSLayoutConstraint(item: label, attribute: .CenterX, relatedBy: .Equal, toItem: view, attribute: .CenterX, multiplier: 1, constant: 0),
            NSLayoutConstraint(item: label, attribute: .CenterY, relatedBy: .Equal, toItem: view, attribute: .CenterY, multiplier: 1, constant: 0)])
    }
}

class FocusTextView: UITextView {
    
    private let blurEffectView = UIVisualEffectView(effect: UIBlurEffect(style: .ExtraLight))

    private let motionEffectGroup = UIMotionEffectGroup()
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    
        selectable = true
        scrollEnabled = false
        clipsToBounds = false
        textContainer.lineBreakMode = .ByTruncatingTail
        textContainerInset = UIEdgeInsetsZero;
        
        blurEffectView.backgroundColor = UIColor.whiteColor().colorWithAlphaComponent(0.6)
        blurEffectView.frame = CGRectInset(bounds, -10, -10)
        blurEffectView.alpha = 0
        blurEffectView.layer.cornerRadius = 10
        blurEffectView.clipsToBounds = true
        insertSubview(blurEffectView, atIndex: 0)
        
        let tap = UITapGestureRecognizer(target: self, action: "tapped:")
        tap.allowedPressTypes = [NSNumber(integer: UIPressType.Select.rawValue)]
        addGestureRecognizer(tap)
        
        let motionRange = 5
        
        let verticalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.y", type: .TiltAlongVerticalAxis)
        verticalMotionEffect.minimumRelativeValue = -motionRange
        verticalMotionEffect.maximumRelativeValue = motionRange
        
        let tiltAngle = CGFloat(2 * M_PI / 180)
        
        var minX = CATransform3DIdentity
        minX.m34 = 1.0 / 500
        minX = CATransform3DRotate(minX, -tiltAngle, 1, 0, 0)
        
        var maxX = CATransform3DIdentity
        maxX.m34 = minX.m34
        maxX = CATransform3DRotate(maxX, tiltAngle, 1, 0, 0)
        
        let verticalTiltEffect = UIInterpolatingMotionEffect(keyPath: "layer.transform", type: .TiltAlongVerticalAxis)
        verticalTiltEffect.minimumRelativeValue =  NSValue(CATransform3D: minX)
        verticalTiltEffect.maximumRelativeValue =  NSValue(CATransform3D: maxX)
        
        self.motionEffectGroup.motionEffects = [verticalMotionEffect, verticalTiltEffect]
    }

    
    func tapped(gesture: UITapGestureRecognizer) {

        if let vc = delegate as? UIViewController {
            let modal = TextPresentationViewController()
            modal.label.attributedText = attributedText
            modal.label.textColor = .whiteColor()
            modal.modalPresentationStyle = .OverFullScreen
            vc.presentViewController(modal, animated: true, completion: nil)
        }
    }
    
    override func canBecomeFocused() -> Bool {
        return true
    }
    
    override func didUpdateFocusInContext(context: UIFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {
        
        if context.nextFocusedView == self {
            coordinator.addCoordinatedAnimations({ () -> Void in
                self.blurEffectView.alpha = 1
                self.addMotionEffect(self.motionEffectGroup)
                }, completion: nil)
        } else if context.previouslyFocusedView == self {
            coordinator.addCoordinatedAnimations({ () -> Void in
                self.blurEffectView.alpha = 0
                self.removeMotionEffect(self.motionEffectGroup)
                }, completion: nil)
        }
    }
    
}