Mark PFInstallation.+currentInstallation as nullable.

Author: nlutsenko

Parse/PFInstallation.h

@@ -47,9 +47,9 @@ PF_TV_UNAVAILABLE PF_WATCH_UNAVAILABLE @interface PFInstallation : PFObject<PFSu
  If this installation is not stored on disk this method will create a new `PFInstallation`
  with `deviceType` and `installationId` fields set to those of the current installation.
 
- @result Returns a `PFInstallation` that represents the currently-running installation.
+ @result Returns a `PFInstallation` that represents the currently-running installation if it could be loaded from disk, otherwise - `nil`.
  */
-+ (instancetype)currentInstallation;
++ (nullable instancetype)currentInstallation;
 
 /**
  *Asynchronously* loads the currently-running installation from disk and returns an instance of it.

ParseStarterProject/OSX/ParseOSXStarterProject-Swift/ParseOSXStarterProject/AppDelegate.swift

@@ -47,8 +47,8 @@ class AppDelegate: NSObject, NSApplicationDelegate {
 
     func application(application: NSApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {
         let installation = PFInstallation.currentInstallation()
-        installation.setDeviceTokenFromData(deviceToken)
-        installation.saveInBackground()
+        installation?.setDeviceTokenFromData(deviceToken)
+        installation?.saveInBackground()
 
         PFPush.subscribeToChannelInBackground("") { (succeeded: Bool, error: NSError?) in
             if succeeded {

ParseStarterProject/iOS/ParseStarterProject-Swift/ParseStarterProject/AppDelegate.swift

@@ -76,8 +76,8 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
 
     func application(application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {
         let installation = PFInstallation.currentInstallation()
-        installation.setDeviceTokenFromData(deviceToken)
-        installation.saveInBackground()
+        installation?.setDeviceTokenFromData(deviceToken)
+        installation?.saveInBackground()
 
         PFPush.subscribeToChannelInBackground("") { (succeeded: Bool, error: NSError?) in
             if succeeded {

ParseStarterProject/watchOS/ParseStarterProject-Swift/ParseStarterProject/AppDelegate.swift

@@ -81,8 +81,8 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
 
     func application(application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {
         let installation = PFInstallation.currentInstallation()
-        installation.setDeviceTokenFromData(deviceToken)
-        installation.saveInBackground()
+        installation?.setDeviceTokenFromData(deviceToken)
+        installation?.saveInBackground()
 
         PFPush.subscribeToChannelInBackground("") { (succeeded: Bool, error: NSError?) in
             if succeeded {