Binding optional to non-optional and vice-versa (#12)

Sources/UIExtensions/Extensions/Binding+Optional.swift

@@ -0,0 +1,42 @@
+//
+//  Binding+ToOptional.swift
+//  UIExtensions
+//
+//  Created by Luiz Rodrigo Martins Barbosa on 14.09.20.
+//  Copyright © 2020 Lautsprecher Teufel GmbH. All rights reserved.
+//
+
+import SwiftUI
+
+extension Binding {
+    /// Transforms a `Binding<Value>` in a `Binding<Optional<Value>>`. This is useful when your
+    /// internal binding allows optional values to be read and set, but your parent control only
+    /// offers binding to a non-Optional type.
+    ///
+    /// You can optionally provide a closure to be called when the inner component sets the wrapped
+    /// value no nil, so your parent control can act on that accordingly.
+    public func toOptional(onSetToNil: @escaping () -> Void = { }) -> Binding<Value?> {
+        Binding<Value?>(
+            get: { self.wrappedValue },
+            set: { newValue in
+                guard let newValue = newValue else {
+                    onSetToNil()
+                    return
+                }
+                self.wrappedValue = newValue
+            }
+        )
+    }
+}
+
+extension Binding {
+    /// Transforms a `Binding<Optional<Value>>` in a `Binding<Value>`. This is useful when your
+    /// internal binding requires a non-nil value, but your parent control only offers binding
+    /// to an Optional type. You must provide a default fallback for when reading a nil value.
+    public func toNonOptional<V>(default fallback: V) -> Binding<V> where Value == V? {
+        Binding<V>(
+            get: { self.wrappedValue ?? fallback },
+            set: { self.wrappedValue = $0 }
+        )
+    }
+}