Flycut/MJCloudKitUserDefaultsSync/README.mdown

### What is this?
A library to sync NSUserDefaults to iCloud via CloudKit.  Based on MKiCloudSync,
by Mugunth Kumar, a clean and simple class to sync NSUserDefaults to iCloud.
Use of CloudKit removes the "clean and simple" but allows use in apps
distributed outside of the App Store.

### Note:
MJCloudKitUserDefaultsSync was recently converted to not be a mess of static members (a style inherited from MKiCloudSync).  The [Recent Changes](#recent-changes) section below describes how to update your code for this change.

### How to use?
1. Drag the two classes and #import the header file in your Application Delegate
2. Call `[[MJCloudKitUserDefaultsSync sharedSync] startWithPrefix:@"sync" withContainerIdentifier:@"iCloud.com.yourCompany.yourProduct"];`
3. Register for Remote Notifications in your applicationDidFinishLaunching.

        // macOS
        - (void)applicationDidFinishLaunching:(NSNotification *)notification
        {
        	// Enable notification from CloudKit
        	[NSApp registerForRemoteNotificationTypes:NSRemoteNotificationTypeNone];// silent push notification!
        
        	//Create our hot key
        	[self toggleMainHotKey:[NSNull null]];
        }
4. Add a NotificationCenter receiver and optional registration handlers as follows

        // macOS:
        - (void)application:(NSApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
        {
        	[[MJCloudKitUserDefaultsSync sharedSync] checkCloudKitUpdates];
        }
        
        // Remote Notifications (APN, aka Push Notifications) are only available on apps distributed via the App Store.
        // To support building for both distribution channels, include the following two methods to detect if Remote Notifications are available and inform MJCloudKitUserDefaultsSync.
        - (void)application:(NSApplication *)application
        didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
        	// Forward the token to your provider, using a custom method.
        	NSLog(@"Registered for remote notifications.");
        	[[MJCloudKitUserDefaultsSync sharedSync] setRemoteNotificationsEnabled:YES];
        }
        
        - (void)application:(NSApplication *)application
        didFailToRegisterForRemoteNotificationsWithError:(NSError *)error {
        	NSLog(@"Remote notification support is unavailable due to error: %@", error);
        	[[MJCloudKitUserDefaultsSync sharedSync] setRemoteNotificationsEnabled:NO];
        }

        // iOS:
        // TBD

### Recent Changes
MJCloudKitUserDefaultsSync recently abandoned the everything-static design it inherited from MKiCloudSync.  Developers now have the option to use a singleton instance or unique instances of the class.  To update your code for this change, using the singleton, use the following changes.

Objective-C
`[MJCloudKitUserDefaultsSync checkCloudKitUpdates];`
to 
`[[MJCloudKitUserDefaultsSync sharedSync] checkCloudKitUpdates];`
(sharedSync is nullable but Objective-C doesn't mind messages sent to nil, so if sharedSync failed to allocate it would run like that line wasn't there.)

Swift
`MJCloudKitUserDefaultsSync.checkCloudKitUpdates()`
to
`MJCloudKitUserDefaultsSync.shared()?.checkCloudKitUpdates()`

### To Do
* Create an xcproj and turn this into a framework so it can be used by both ARC and non-ARC projects.  It is currently being used by an old non-ARC project, so it isn't ARC for now.
* Consider switching to ARC.
* Evaluate the current model, inherited from MKiCloudSync, of being built on class methods and static variables vs containing the variables in the class and using a singleton vs possibilities of multiple instances of the class.
* Evaluate capability to synchronize other dictionaries beyond just NSUserDefaults.
* updateFromiCloud could perhaps include the old and new values in the change list provided to sendChangeNotifications to provide to interested parties.

### Compatibility
Care has been taken to enable this library to use newer and better CloudKit capabilities introduced in macOS 10.12 (Sierra) while maintaining compatibility with OS X 10.10 (Yosemite) where CloudKit was first introduced.  The initial project using this library targets Mac OS X 10.7 (Lion), though the CloudKit portions of that project won't do anything on that release.

### Notes
This is currently a beta release.  This initial commit has been demonstrated to
work but warrants further evaluation and testing.  It includes copious logging
statements, a bit of debug code, a bit of commented-out stuff that can be
removed, and a bit of commented-out stuff that should maybe be restored.  It has
not yet been verified to be of consistent style.

See [Flycut](http://github.com/MarkJerde/Flycut) for an example of
MJCloudKitUserDefaultsSync in use.

MJCloudKitUserDefaultsSync is based on Mugunth Kumar's MKiCloudSync, though it
is massively different as a result of using CloudKit and having a few additional
features.  It does, however, retain about half of Mugunth Kumar's code, owing to
the simplicity of his original solution.  Given their differences, in use of
CloudKit vs iCloud key-value store, the two are named and maintained
independently to avoid confusion.  If you are looking for a simple solution for
apps distributed through the App Store, MJCloudKitUserDefaultsSync will work but
consider MKiCloudSync.

Read the [blog post](http://blog.mugunthkumar.com/coding/ios-code-mkicloudsync-sync-your-nsuserdefaults-to-icloud-with-a-single-line-of-code) for more on Mugunth Kumar's original solution.
### License
Copyright (C) 2017 by Mark Jerde

Portions Copyright (C) 2011-2020 by Steinlogic

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

As a side note, you might also consider

1) tweeting about this mentioning @mark_a_jerde

2) A paypal donation to mark.a.jerde@gmail.com

3) tweeting about this mentioning @mugunthkumar for his original contributions

4) A paypal donation to mugunth.kumar@gmail.com