Remove hardcoded dependency on RunLoop.main.

By making use of the Scheduler abstraction and the SwiftUI environment, we can
make it possible to remove the asynchronous behaviour in e.g. snapshot tests by
setting the responderScheduler environment key to .immediate (or any other
test scheduler).

Author: lukeredpath

Package.swift

@@ -12,12 +12,15 @@ let package = Package(
             targets: ["ResponsiveTextField"]),
     ],
     dependencies: [
-        .package(name: "SnapshotTesting", url: "https://github.com/pointfreeco/swift-snapshot-testing.git", from: "1.8.1")
+        .package(name: "SnapshotTesting", url: "https://github.com/pointfreeco/swift-snapshot-testing.git", from: "1.8.1"),
+        .package(name: "combine-schedulers", url: "https://github.com/pointfreeco/combine-schedulers.git", from: "0.5.3")
     ],
     targets: [
         .target(
             name: "ResponsiveTextField",
-            dependencies: []),
+            dependencies: [
+                .product(name: "CombineSchedulers", package: "combine-schedulers")
+            ]),
         .testTarget(
             name: "ResponsiveTextFieldTests",
             dependencies: ["ResponsiveTextField", "SnapshotTesting"],

ResponsiveTextField.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -5,6 +5,7 @@
 //  Created by Luke Redpath on 14/03/2021.
 //
 
+import CombineSchedulers
 import SwiftUI
 
 // MARK: - Environment Keys
@@ -29,6 +30,10 @@ extension ResponsiveTextField {
     fileprivate struct FirstResponderDemandKey: EnvironmentKey {
         static let defaultValue: FirstResponderDemand? = nil
     }
+
+    fileprivate struct ResponderSchedulerKey: EnvironmentKey {
+        static let defaultValue: AnySchedulerOf<RunLoop> = .main
+    }
 }
 
 // MARK: - Environment Values
@@ -58,4 +63,9 @@ extension EnvironmentValues {
         get { self[ResponsiveTextField.FirstResponderDemandKey.self] }
         set { self[ResponsiveTextField.FirstResponderDemandKey.self] = newValue }
     }
+
+    public var responderScheduler: AnySchedulerOf<RunLoop> {
+        get { self[ResponsiveTextField.ResponderSchedulerKey.self] }
+        set { self[ResponsiveTextField.ResponderSchedulerKey.self] = newValue }
+    }
 }

Sources/ResponsiveTextField/ResponsiveTextField+EnvironmentValues.swift

@@ -5,6 +5,7 @@
 import Combine
 import UIKit
 import SwiftUI
+import CombineSchedulers
 
 // MARK: - Main Interface
 
@@ -71,6 +72,9 @@ public struct ResponsiveTextField {
     @Environment(\.textFieldTextAlignment)
     var textAlignment: NSTextAlignment
 
+    @Environment(\.responderScheduler)
+    private var responderScheduler: AnySchedulerOf<RunLoop>
+
     /// A calllback function that will be called whenever the first responder state changes.
     var onFirstResponderStateChanged: FirstResponderStateChangeHandler?
 
@@ -344,25 +348,25 @@ extension ResponsiveTextField: UIViewRepresentable {
 
         switch (uiView.isFirstResponder, firstResponderDemand?.wrappedValue) {
         case (true, .shouldResignFirstResponder):
-            RunLoop.main.schedule { uiView.resignFirstResponder() }
+            responderScheduler.schedule { uiView.resignFirstResponder() }
         case (false, .shouldBecomeFirstResponder):
-            RunLoop.main.schedule { uiView.becomeFirstResponder() }
+            responderScheduler.schedule { uiView.becomeFirstResponder() }
         case (_, nil):
             // If there is no demand then there's nothing to do.
             break
         default:
             // If the current responder state matches the demand then
             // the demand is already fulfilled so we can just reset it.
-            resetFirstResponderDemandAfterViewUpdate()
+            resetFirstResponderDemand()
         }
     }
 
-    fileprivate func resetFirstResponderDemandAfterViewUpdate() {
+    fileprivate func resetFirstResponderDemand() {
         // Because the first responder demand will trigger a view
         // update when it is set, we need to wait until the next
         // runloop tick to reset it back to nil to avoid runtime
         // warnings.
-        RunLoop.main.schedule {
+        responderScheduler.schedule {
             firstResponderDemand?.wrappedValue = nil
         }
     }
@@ -382,7 +386,7 @@ extension ResponsiveTextField: UIViewRepresentable {
             if let canBecomeFirstResponder = parent.onFirstResponderStateChanged?.canBecomeFirstResponder {
                 let shouldBeginEditing = canBecomeFirstResponder()
                 if !shouldBeginEditing {
-                    parent.resetFirstResponderDemandAfterViewUpdate()
+                    parent.resetFirstResponderDemand()
                 }
                 return shouldBeginEditing
             }
@@ -391,14 +395,14 @@ extension ResponsiveTextField: UIViewRepresentable {
 
         public func textFieldDidBeginEditing(_ textField: UITextField) {
             parent.onFirstResponderStateChanged?(true)
-            parent.resetFirstResponderDemandAfterViewUpdate()
+            parent.resetFirstResponderDemand()
         }
 
         public func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
             if let canResignFirstResponder = parent.onFirstResponderStateChanged?.canResignFirstResponder {
                 let shouldEndEditing = canResignFirstResponder()
                 if !shouldEndEditing {
-                    parent.resetFirstResponderDemandAfterViewUpdate()
+                    parent.resetFirstResponderDemand()
                 }
                 return shouldEndEditing
             }
@@ -407,7 +411,7 @@ extension ResponsiveTextField: UIViewRepresentable {
 
         public func textFieldDidEndEditing(_ textField: UITextField) {
             parent.onFirstResponderStateChanged?(false)
-            parent.resetFirstResponderDemandAfterViewUpdate()
+            parent.resetFirstResponderDemand()
         }
 
         public func textFieldShouldReturn(_ textField: UITextField) -> Bool {