viewDidLoad
viewWillAppear
viewDidDisappear
override func viewDidLoad() { super.viewDidLoad() ref = Firebase(url: "https://<YOUR-FIREBASE-APP>.firebaseio.com") }
- (void)viewDidLoad { [super viewDidLoad]; self.ref = [[Firebase alloc] initWithUrl:@"https://<YOUR-FIREBASE-APP>.firebaseio.com"]; }
UIViewController
class ViewController : UIViewController { var ref: Firebase! override func viewDidLoad() { super.viewDidLoad() ref = Firebase(url: "https://<YOUR-FIREBASE-APP>.firebaseio.com") } }
Firebase
nil
class ViewController : UIViewController { let ref = Firebase(url: "https://<YOUR-FIREBASE-APP>.firebaseio.com") }
class ViewController : UIViewController { // This won't compile :( let ref = Firebase(url: "https://my.firebaseio.com/\(myCoolProperty)") }
override func viewWillAppear(animated: Bool) { super.viewWillAppear(animated) ref.observeEventType(.Value) { (snap: FDataSnapshot!) in print (snap.value) } }
- (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; [self.ref observeEventType:FEventTypeValue withBlock:^(FDataSnapshot *snapshot) { NSLog(@"%@", snapshot.value); }]; }
class ViewController : UIViewController { var ref: Firebase! var handle: UInt! override func viewWillAppear(animated: Bool) { super.viewWillAppear(animated) handle = ref.observeEventType(.Value) { (snap: FDataSnapshot) in print (snap.value) } } }
@interface ViewController() @property (nonatomic, strong) Firebase *ref; @property FirebaseHandle handle; @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; self.ref = [[Firebase alloc] initWithUrl:@"https://<YOUR-FIREBASE-APP>.firebaseio.com"]; } - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; self.handle = [self.ref observeEventType:FEventTypeValue withBlock:^(FDataSnapshot *snapshot) { NSLog(@"%@", snapshot.value); }]; } @end
FirebaseHandle
typealias
UInt
handle
override func viewDidDisappear(animated: Bool) { super.viewDidDisappear(animated) ref.removeObserverWithHandle(handle) }
-(void)viewDidDisappear:(BOOL)animated { [super viewDidDisappear:animated]; [self.ref removeObserverWithHandle:self.handle]; }
A leaky listener is a listener that is consuming memory to store data that isn't displayed or accessed. This is especially an issue when navigating using a UINavigationController, since the root controller isn’t removed from memory when navigating to a detail controller. This means a root controller will continue to synchronize data if the listener isn't removed when navigating away. This action takes up needless bandwidth and memory.
UINavigationController
The thought of removing the listener might sound unappealing. You may think you need to keep your listener open to avoid downloading the same data again, but this is unnecessary. Firebase SDKs come baked in with caching and offline data persistence. These features keep the client from having to fetch recently downloaded data.
AppDelegate
class AppDelegate: UIResponder, UIApplicationDelegate { var window: UIWindow? override init() { Firebase.defaultConfig().persistenceEnabled = true } }
@implementation AppDelegate - (instancetype)init { self = [super init]; if (self) { [[Firebase defaultConfig] setPersistenceEnabled:YES]; } return self; } @end
application:didFinishLaunchingWithOptions
Check out this gist to see the final version of the UIViewController.
