Clipboard hasStrings method on iOS (#19859)

* Implement Clipboard hasStrings method on iOS

* Test call to hasStrings

* Formatting fixes

* Move test to its own file

* Alphabetical order

* Update licenses

* arguments nil instead of empty dictionary

* Guarantee hasStrings will be true when tested

* Formatting

Author: justinmc

ci/licenses_golden/licenses_flutter

@@ -929,6 +929,7 @@ FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterOverlay
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterOverlayView.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformPlugin.h
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformPlugin.mm
+FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformPluginTest.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformViewsTest.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.h

shell/platform/darwin/ios/BUILD.gn

@@ -171,6 +171,7 @@ source_set("ios_test_flutter_mrc") {
   ]
   sources = [
     "framework/Source/FlutterEnginePlatformViewTest.mm",
+    "framework/Source/FlutterPlatformPluginTest.mm",
     "framework/Source/FlutterPlatformViewsTest.mm",
     "framework/Source/accessibility_bridge_test.mm",
   ]

shell/platform/darwin/ios/framework/Source/FlutterPlatformPlugin.mm

@@ -88,6 +88,8 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
   } else if ([method isEqualToString:@"Clipboard.setData"]) {
     [self setClipboardData:args];
     result(nil);
+  } else if ([method isEqualToString:@"Clipboard.hasStrings"]) {
+    result([self clipboardHasStrings]);
   } else {
     result(FlutterMethodNotImplemented);
   }
@@ -248,4 +250,16 @@ - (void)setClipboardData:(NSDictionary*)data {
   }
 }
 
+- (NSDictionary*)clipboardHasStrings {
+  bool hasStrings = false;
+  UIPasteboard* pasteboard = [UIPasteboard generalPasteboard];
+  if (@available(iOS 10, *)) {
+    hasStrings = pasteboard.hasStrings;
+  } else {
+    NSString* stringInPasteboard = pasteboard.string;
+    hasStrings = stringInPasteboard != nil;
+  }
+  return @{@"value" : @(hasStrings)};
+}
+
 @end

shell/platform/darwin/ios/framework/Source/FlutterPlatformPluginTest.mm

@@ -0,0 +1,51 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import <XCTest/XCTest.h>
+
+#import "flutter/shell/platform/darwin/common/framework/Headers/FlutterBinaryMessenger.h"
+#import "flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h"
+#import "flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformPlugin.h"
+#import "flutter/shell/platform/darwin/ios/platform_view_ios.h"
+#import "third_party/ocmock/Source/OCMock/OCMock.h"
+
+@interface FlutterPlatformPluginTest : XCTestCase
+@end
+
+@implementation FlutterPlatformPluginTest
+
+- (void)testHasStrings {
+  FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"test" project:nil];
+  std::unique_ptr<fml::WeakPtrFactory<FlutterEngine>> _weakFactory =
+      std::make_unique<fml::WeakPtrFactory<FlutterEngine>>(engine);
+  FlutterPlatformPlugin* plugin =
+      [[FlutterPlatformPlugin alloc] initWithEngine:_weakFactory->GetWeakPtr()];
+
+  // Set some string to the pasteboard.
+  __block bool calledSet = false;
+  FlutterResult resultSet = ^(id result) {
+    calledSet = true;
+  };
+  FlutterMethodCall* methodCallSet =
+      [FlutterMethodCall methodCallWithMethodName:@"Clipboard.setClipboardData"
+                                        arguments:@{@"text" : @"some string"}];
+  [plugin handleMethodCall:methodCallSet result:resultSet];
+  XCTAssertEqual(calledSet, true);
+
+  // Call hasStrings and expect it to be true.
+  __block bool called = false;
+  __block bool value;
+  FlutterResult result = ^(id result) {
+    called = true;
+    value = result[@"value"];
+  };
+  FlutterMethodCall* methodCall =
+      [FlutterMethodCall methodCallWithMethodName:@"Clipboard.hasStrings" arguments:nil];
+  [plugin handleMethodCall:methodCall result:result];
+
+  XCTAssertEqual(called, true);
+  XCTAssertEqual(value, true);
+}
+
+@end