feat: Add PFObject.isDataAvailableForKey to check if data is available for individual key (#1756)

Author: dplewis

Parse/Parse/Internal/Object/PFObjectPrivate.h

@@ -202,8 +202,6 @@
 - (void)setHasBeenFetched:(BOOL)fetched;
 - (void)_setDeleted:(BOOL)deleted;
 
-- (BOOL)isDataAvailableForKey:(NSString *)key;
-
 - (BOOL)_hasChanges;
 - (BOOL)_hasOutstandingOperations;
 - (PFOperationSet *)unsavedChanges;

Parse/Parse/Source/PFObject.h

@@ -399,6 +399,13 @@ NS_REQUIRES_PROPERTY_DEFINITIONS
  */
 @property (nonatomic, assign, readonly, getter=isDataAvailable) BOOL dataAvailable;
 
+/**
+ Checks whether the `PFObject` has data for given key
+ 
+ @return `YES` if data is available for given key
+ */
+- (BOOL)isDataAvailableForKey:(NSString *)key;
+
 #if TARGET_OS_IOS
 
 /**