Making compatible with Swift 5.2

Sources/Snap/SnapCalculator.swift

@@ -9,7 +9,7 @@ struct SnapPointCalculator<State: SnapState> {
         let contentHeight: CGFloat
 
         static var zero: SnapResult {
-            return SnapResult(state: .invisible, offset: UIScreen.main.bounds.height, contentHeight: 0)
+            return SnapResult(state: .invisibleState, offset: UIScreen.main.bounds.height, contentHeight: 0)
         }
     }
 
@@ -26,6 +26,8 @@ struct SnapPointCalculator<State: SnapState> {
     let results: [SnapResult]
 
     init(results: [SnapResult]) {
+        assert(!results.isEmpty, "Invalid Empty Calculation")
+
         let ranges = results.pairs().map { SnapRange(upper: $0, lower: $1) }
         assert(ranges.allSatisfy { $0.upper.offset < $0.lower.offset }, "Ranges are invalidd")
         self.ranges = ranges
@@ -44,9 +46,9 @@ struct SnapPointCalculator<State: SnapState> {
         let matchingRanges = ranges.filter { $0.offsetRange.contains(cardTopEdgeLocation) }
         guard let range = drag.translation.height > 0 ? matchingRanges.last : matchingRanges.first else {
             if drag.translation.height < 0 {
-                return ranges.first?.upper ?? .zero
+                return results.first!
             } else {
-                return ranges.last?.lower ?? .zero
+                return results.last!
             }
         }
 

Sources/Snap/SnapDrawer.swift

@@ -31,7 +31,7 @@ public struct SnapDrawer<StateType: SnapState, Background : View, Content: View>
         self.state = state
         self.background = background
         self.content = content
-        self._currentResult = State(initialValue: calculator(state: .large))
+        self._currentResult = State(initialValue: calculator(state: .largeState))
         self.minDrag = self.calculator.results.first?.offset ?? 0
         self.maxDrag = self.calculator.results.last?.offset ?? 0
     }

Sources/Snap/SnapState.swift

@@ -4,8 +4,10 @@ import Foundation
 public protocol SnapState: Equatable {
     associatedtype Visible
 
-    static var large: Self { get }
-    static var invisible: Self { get }
+    // State postfix was added until we upgrade to Swift 5.3 and get
+    // Enum cases as protocol witnesses
+    static var largeState: Self { get }
+    static var invisibleState: Self { get }
 
     var visible: Visible? { get }
 }
@@ -15,6 +17,9 @@ public enum ModalSnapState: SnapState {
         case large
     }
 
+    public static let largeState: ModalSnapState = .large
+    public static let invisibleState: ModalSnapState = .invisible
+
     case large
     case invisible
 
@@ -33,6 +38,9 @@ public enum OvercastSnapState: SnapState {
         case large
         case tiny
     }
+
+    public static let largeState: OvercastSnapState = .large
+    public static let invisibleState: OvercastSnapState = .invisible
 
     case large
     case tiny
@@ -57,6 +65,9 @@ public enum AppleMapsSnapState: SnapState {
         case tiny
     }
 
+    public static let largeState: AppleMapsSnapState = .large
+    public static let invisibleState: AppleMapsSnapState = .invisible
+
     case large
     case medium
     case tiny