Checking the pasteboard for dynamic links in ios14 (#5905)

* Checking the first pasteboard item in ios14

* Cleaned up method and added ifdef

* Renamed variable

* Style

* Refactored method

* Using another url detecting api

* Made sure pasteboardContents is initialized

* Changelog

* Update Changelog

* Removed trailing space

Author: ncooke3

FirebaseDynamicLinks/CHANGELOG.md

@@ -1,3 +1,6 @@
+# Unversioned
+- [fixed] Reduce frequency of iOS14 pasteboard notifications by only reading from it when it contains URL(s). (#5905)
+
 # v4.3.0
 - [changed] Functionally neutral updated import references for dependencies. (#5824)
 

FirebaseDynamicLinks/Sources/FIRDLDefaultRetrievalProcessV2.m

@@ -270,7 +270,7 @@ - (void)markCompleted {
 
 - (nullable NSURL *)uniqueMatchLinkToCheck {
   _clipboardContentAtMatchProcessStart = nil;
-  NSString *pasteboardContents = [UIPasteboard generalPasteboard].string;
+  NSString *pasteboardContents = [self retrievePasteboardContents];
   NSInteger linkStringMinimumLength =
       expectedCopiedLinkStringSuffix.length + /* ? or & */ 1 + /* http:// */ 7;
   if ((pasteboardContents.length >= linkStringMinimumLength) &&
@@ -296,6 +296,18 @@ - (nullable NSURL *)uniqueMatchLinkToCheck {
   return nil;
 }
 
+- (NSString *)retrievePasteboardContents {
+  NSString *pasteboardContents = @"";
+  if (@available(iOS 10.0, *)) {
+    if ([[UIPasteboard generalPasteboard] hasURLs]) {
+      pasteboardContents = [UIPasteboard generalPasteboard].string;
+    }
+  } else {
+    pasteboardContents = [UIPasteboard generalPasteboard].string;
+  }
+  return pasteboardContents;
+}
+
 - (void)clearUsedUniqueMatchLinkToCheckFromClipboard {
   // See discussion in b/65304652
   // We will clear clipboard after we used the unique match link from the clipboard