87 lines
2.1 KiB
Swift
87 lines
2.1 KiB
Swift
|
import Foundation
|
||
|
|
|
||
|
|
class VisibilityViewManager {
|
||
|
|
static let shared = VisibilityViewManager()
|
||
|
|
|
||
|
|
private let views = NSHashTable<VisibilityView>(options: .weakMemory)
|
||
|
|
private var currentlyActiveView: VisibilityView?
|
||
|
|
private var screenHeight: CGFloat = UIScreen.main.bounds.height
|
||
|
|
private var prevCount = 0
|
||
|
|
|
||
|
|
func addView(_ view: VisibilityView) {
|
||
|
|
self.views.add(view)
|
||
|
|
|
||
|
|
if self.prevCount == 0 {
|
||
|
|
self.updateActiveView()
|
||
|
|
}
|
||
|
|
self.prevCount = self.views.count
|
||
|
|
}
|
||
|
|
|
||
|
|
func removeView(_ view: VisibilityView) {
|
||
|
|
self.views.remove(view)
|
||
|
|
self.prevCount = self.views.count
|
||
|
|
}
|
||
|
|
|
||
|
|
func updateActiveView() {
|
||
|
|
DispatchQueue.main.async {
|
||
|
|
var activeView: VisibilityView?
|
||
|
|
|
||
|
|
if self.views.count == 1 {
|
||
|
|
let view = self.views.allObjects[0]
|
||
|
|
if view.isViewableEnough() {
|
||
|
|
activeView = view
|
||
|
|
}
|
||
|
|
} else if self.views.count > 1 {
|
||
|
|
let views = self.views.allObjects
|
||
|
|
var mostVisibleView: VisibilityView?
|
||
|
|
var mostVisiblePosition: CGRect?
|
||
|
|
|
||
|
|
views.forEach { view in
|
||
|
|
if !view.isViewableEnough() {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
guard let position = view.getPositionOnScreen() else {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
if position.minY >= 150 {
|
||
|
|
if mostVisiblePosition == nil {
|
||
|
|
mostVisiblePosition = position
|
||
|
|
}
|
||
|
|
|
||
|
|
if let unwrapped = mostVisiblePosition,
|
||
|
|
position.minY <= unwrapped.minY {
|
||
|
|
mostVisibleView = view
|
||
|
|
mostVisiblePosition = position
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
activeView = mostVisibleView
|
||
|
|
}
|
||
|
|
|
||
|
|
if activeView == self.currentlyActiveView {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
self.clearActiveView()
|
||
|
|
if let view = activeView {
|
||
|
|
self.setActiveView(view)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
private func clearActiveView() {
|
||
|
|
if let currentlyActiveView = self.currentlyActiveView {
|
||
|
|
currentlyActiveView.setIsCurrentlyActive(isActive: false)
|
||
|
|
self.currentlyActiveView = nil
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
private func setActiveView(_ view: VisibilityView) {
|
||
|
|
view.setIsCurrentlyActive(isActive: true)
|
||
|
|
self.currentlyActiveView = view
|
||
|
|
}
|
||
|
|
}
|