Add get and set server (#1464)

* add server property and setServer

* removed unnecessary exception when setting server before client is initialized

* amended docs

Author: mtrezza

Parse/Parse/Parse.h

@@ -106,6 +106,16 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, nullable, readonly, class) ParseClientConfiguration *currentConfiguration;
 
+/**
+ Sets the server URL to connect to Parse Server. The local client cache is not cleared.
+ @discussion This can be used to update the server URL after this client has been initialized, without having to destroy this client. An example use case is
+ server connection failover, where the clients connects to another URL if the server becomes unreachable at the current URL.
+ @warning The new server URL must point to a Parse Server that connects to the same database. Otherwise, issues may arise
+ related to locally cached data or delayed methods such as saveEventually.
+ @param server  The server URL to set.
+ */
++ (void)setServer:(nonnull NSString *)server;
+
 /**
  The current application id that was used to configure Parse framework.
  */
@@ -120,6 +130,11 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (nullable NSString *)getClientKey PARSE_DEPRECATED("Use clientKey property.");
 
+/**
+ The current server URL to connect to Parse Server.
+ */
+@property (nonatomic, nullable, readonly, class) NSString *server;
+
 ///--------------------------------------
 #pragma mark - Enabling Local Datastore
 ///--------------------------------------

Parse/Parse/Parse.m

@@ -89,6 +89,10 @@ + (void)initializeWithConfiguration:(ParseClientConfiguration *)configuration {
     [[self parseModulesCollection] parseDidInitializeWithApplicationId:configuration.applicationId clientKey:configuration.clientKey];
 }
 
++ (void)setServer:(nonnull NSString *)server {
+    [PFInternalUtils setParseServer:server];
+}
+
 + (nullable ParseClientConfiguration *)currentConfiguration {
     return currentParseManager_.configuration;
 }
@@ -113,6 +117,10 @@ + (nullable NSString *)getClientKey {
     return [self clientKey];
 }
 
++ (nullable NSString *)server {
+    return [[PFInternalUtils parseServerURLString] copy];
+}
+
 ///--------------------------------------
 #pragma mark - Extensions Data Sharing
 ///--------------------------------------