iOS Chromoting Client

remoting/ios/data_store.mm

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+#import "remoting/ios/data_store.h"
+
+@interface DataStore (Private)
+- (NSString*)itemArchivePath;
+@end
+
+@implementation DataStore {
+ @private
+  NSMutableArray* _allHosts;
+  NSManagedObjectContext* _context;
+  NSManagedObjectModel* _model;
+}
+
+// Create or Get a static data store
++ (DataStore*)sharedStore {
+  static DataStore* sharedStore = nil;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken,
+                ^{ sharedStore = [[super allocWithZone:nil] init]; });

[dcaiafa, 2014/03/19 01:14:15]

Why allocWithZone instead of just alloc?

[aboone, 2014/03/21 16:42:07]

allocWithZone has been overridden to always return the singleton.  If [super
alloc] was used then our version of allocWithZone would be called impliciently,
and an infinite loop would occur.

There is an explanation of it here
http://stackoverflow.com/questions/11962913/creating-a-singleton-with-allocwi...

+
+  return sharedStore;
+}
+
+// General methods
++ (id)allocWithZone:(NSZone*)zone {
+  return [self sharedStore];
+}
+
+// Load data store from SQLLite backing store
+- (id)init {
+  self = [super init];
+
+  if (self) {
+    // Read in ChromotingModel.xdatamodeld
+    _model = [NSManagedObjectModel mergedModelFromBundles:nil];
+
+    NSPersistentStoreCoordinator* psc = [[NSPersistentStoreCoordinator alloc]
+        initWithManagedObjectModel:_model];
+
+    NSString* path = [self itemArchivePath];
+    NSURL* storeUrl = [NSURL fileURLWithPath:path];
+
+    NSError* error = nil;
+
+    if (![psc
+             addPersistentStoreWithType:NSSQLiteStoreType
+                          configuration:nil
+                                    URL:storeUrl
+                                options:
+                                    @{

[dcaiafa, 2014/03/19 01:14:15]

Maybe use a intermediate local variable for this NSDictionary to improve
readability, here and below. 

[aboone, 2014/03/21 16:42:07]

Done.

+                                      NSMigratePersistentStoresAutomaticallyOption :
+                                      @YES,
+                                      NSInferMappingModelAutomaticallyOption :
+                                      @YES
+                                    }
+                                  error:&error]) {
+      // An incompatiable version of the store exists, delete it and start over
+      [[NSFileManager defaultManager] removeItemAtURL:storeUrl error:nil];
+
+      [psc
+          addPersistentStoreWithType:NSSQLiteStoreType
+                       configuration:nil
+                                 URL:storeUrl
+                             options:
+                                 @{
+                                   NSMigratePersistentStoresAutomaticallyOption :
+                                   @YES
+                                 }
+                               error:&error];
+      [NSException raise:@"Open failed"
+                  format:@"Reason: %@", [error localizedDescription]];
+    }
+
+    // Create the managed object context
+    _context = [[NSManagedObjectContext alloc] init];
+    [_context setPersistentStoreCoordinator:psc];
+
+    // The managed object context can manage undo, but we don't need it
+    [_context setUndoManager:nil];
+
+    _allHosts = nil;
+  }
+  return self;
+}
+
+// Commiting to backing store
+- (BOOL)saveChanges {
+  NSError* err = nil;
+  BOOL successful = [_context save:&err];
+  return successful;
+}
+
+// Looking up the backing store path
+- (NSString*)itemArchivePath {
+  NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(
+      NSDocumentDirectory, NSUserDomainMask, YES);
+
+  // Get one and only document directory from that list
+  NSString* documentDirectory = [documentDirectories objectAtIndex:0];
+
+  return [documentDirectory stringByAppendingPathComponent:@"store.data"];
+}
+
+// Return an array of all known hosts, if the list hasn't been loaded yet, then
+// load it now
+- (NSArray*)allHosts {
+  if (!_allHosts) {
+    NSFetchRequest* request = [[NSFetchRequest alloc] init];
+
+    NSEntityDescription* e =
+        [[_model entitiesByName] objectForKey:@"HostPreferences"];
+
+    [request setEntity:e];
+
+    NSError* error;
+    NSArray* result = [_context executeFetchRequest:request error:&error];
+    if (!result) {
+      [NSException raise:@"Fetch failed"
+                  format:@"Reason: %@", [error localizedDescription]];
+    }
+    _allHosts = [result mutableCopy];
+  }
+
+  return _allHosts;
+}
+
+// Return a HostPreferences if it already exists, otherwise create a new
+// HostPreferences to use
+- (const HostPreferences*)createHost:(NSString*)hostId {
+
+  const HostPreferences* p = [self getHostForId:hostId];
+
+  if (p == nil) {
+    p = [NSEntityDescription insertNewObjectForEntityForName:@"HostPreferences"
+                                      inManagedObjectContext:_context];
+    p.hostId = hostId;
+    [_allHosts addObject:p];
+  }
+  return p;
+}
+
+- (void)removeHost:(HostPreferences*)p {
+  [_context deleteObject:p];
+  [_allHosts removeObjectIdenticalTo:p];
+}
+
+// Search the store for any matching HostPreferences
+// return the 1st match or nil
+- (const HostPreferences*)getHostForId:(NSString*)hostId {
+  NSFetchRequest* request = [[NSFetchRequest alloc] init];
+
+  NSEntityDescription* e =
+      [[_model entitiesByName] objectForKey:@"HostPreferences"];
+  [request setEntity:e];
+
+  NSPredicate* predicate =
+      [NSPredicate predicateWithFormat:@"(hostId = %@)", hostId];
+  [request setPredicate:predicate];
+
+  NSError* error;
+  NSArray* result = [_context executeFetchRequest:request error:&error];
+  if (!result) {
+    [NSException raise:@"Fetch failed"
+                format:@"Reason: %@", [error localizedDescription]];
+  }
+
+  for (HostPreferences* curHost in result) {
+    return curHost;
+  }
+  return nil;
+}
+
+@end