• App Switcher
• iOS6 & iOS7
• Background fetching
• Remote notification
• Background transfers

                        - (void)application:(UIApplication *)application
performFetchWithCompletionHandler:(void (^)(UIBackgroundFetchResult result)) completionHandler

• UIBackgroundFetchResultNewData / NoData / Failed

 - (void)setMinimumBackgroundFetchInterval:(NSTimeInterval)minInterval;

• UIApplicationBackgroundFetchIntervalMinimum
• UIApplicationBackgroundFetchIntervalNever

              - (void)application:(UIApplication *)application
didReceiveRemoteNotification:(NSDictionary *)userInfo
       fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result)) completionHandler;

• before remote notification is displayed
• regardless of the state of your app
• your app has up to 30 seconds

                            - (void)application:(UIApplication *)application
handleEventForBackgroundURLSession:(NSString *)identifier
                           completionHandler:(void (^)())completionHandler;

• Discovery phase
• Session phase
• Programmatic discovery
• Security

• Peer
• Advertiser
• Browser

//identify yourself
MCPeerID *myPeerID = [[MCPeerID alloc] initWithName:@"Oscar"];

//create a session
MCSession *session = [[MCSession alloc] initWithPeer:myPeerID];
session.delegate = self;

//start advertising yourself
MCAdvertiserAssistant *assistant = 
[[MCAdvertiserAssistant alloc] initWithServiceType:type discoveryInfo:nil session:session];
[assistant start];

//MCSessionStateNotConnected/Connecting/Connected)
session:peer:didChangeState: 

MCBrowserViewController *browser = [[MCBrowserViewController] alloc] 
                                                           initWithServiceType:serviceType 
                                                           session:session];
browser.delegte = self;
[self presentViewController:browser animated:YES compiltion:nil];

- (BOOL)sendData:(NSData *)data
               toPeers:(NSArray *)peerIDs
            withMode:(MCSessionSendDataMode)mode
                   error:(NSError **)error

- (void)sendResourceAtURL:(NSURL *)resourceURL
                             toPeer:(NSArray *)peerIDs
                     withTimeout:(NSTimeInterval)timeout
              completionHandler:(void (^)(NSError *error))completehandler

- (NSOutputStream *)startStreamstartStreamWithName:(NSString *)streamName
                                                                  toPeer:(MCPeerID *)peerID
                                                                     error:(NSError **)error

session:didReceiveData:fromPeer:
session:didReceiveResourceAtURL:fromPeer:
session:didReceiveStream:withName:fromPeer:

• MCSessionSendDataReliable
• Application critical data
• Retransmissions
• In order delivery
• MCSessionSendDataUnreliable
• Time sensitive data
• No delivery guarantees
• No order guarantees

[session disconnect];

• Advertising
• Browsing
• Inviting

MCNearbyServiceAdvertiser *advertiser = [[MCNearbyServiceAdvertiser alloc] 
                                                               initWithPeer:myPeerID 
                                                             discoveryInfo:info 
                                                               serviceType:type];
advertiser.delegate = self;
[advertiser startAdvertisingPeer];

MCNearbyServiceBrowser *browser = [[MCNearbyServiceBrowser alloc] 
                                                          initWithPeer:myPeerID 
                                                          serviceType:serviceType];
browser.delegate = self;
[browser startBrowsingForPeers];

    - (void)browser:(MCNearbyServiceBrowser *)browser
           foundPeer:(MCPeerID *)peerID
withDiscoveryInfo:(NSDictionary *)info

- (void)browser:(MCNearbyServiceBrowser *)browser lostPeer:(MCPeerID *)peerID

[browser invitePeer:peerID toSession:session withContext:context timeout:timeout];

                - (void)advertiser:(MCNearbyServiceAdvertiser *)advertiser
didReceiveInvitationFromPeer:(MCPeerID *)peerID
                      withContext:(NSData *)context
                invitationHandler:(void (^)(BOOL accept, MCSession *session))invitationHandler

• Push Notification for Websites
• Objective-C -- JavaScript

• Local vs Push
• Subscribing
• Unsubscribing
• Delivering
• Implementation

• Get website push certificate
• Add support to your server
• Query permission
• Request permission
• Write web service backend
• Send push notification

//result.permission = "default"/"denied"/"granted"
//result.deviceToken = "...."
var result = window.safari.pushNotification.permission( websitePushID );

window.safari.pushNotification.requestPermission(
    webServiceURL,
    websitePushID,
    userInfo,
    callback
);

//if user confirms
callback({
    permission: "granted",
    deviceToken: "...."
});

{
    "aps": {
        "alert": {
            "title": "Flight A109 Gate Changed",
            "body": "Your gate has changed to A4",
            "action": "View"
        },
        "url-args": ["gate-change", "A109"]
    }
}

• Objective-C > JavaScript
• JavaScript > Objective-C

#import <JavaScriptCore/JavaScriptCore.h>

int main(){
    JSContext *context = [[JSContext alloc] init];
    JSValue *result = [context evaluateScript:@"2+2"];
    NSLog(@"2+2=%d", [result toInt32]);
    
    return 0;
}

var factorial = function(n){
    if (n<0) return;
    if (n===0) return 1;
    return n * factorial(n-1);
};

NSString *factorialScript = ...;
[context evaluateScript:factorialScript];

JSValue *function = context[@"factorial"];
JSValue *result = [function callWithArguments:@[@5]];
NSLog(@"factorial(5) = %d", [result toInt32]);

• Blocks
• js functions
• JSExport protocol
• js objects

context[@"makeNSColor"] = ^(NSDictionary *rgb){
    float r = [color[@"red"] floatValue];
    float g = [color[@"green"] floatValue];
    float b = [color[@"blue"] floatValue];
    return [NSColor colorWithRed:(r / 255.0f)
                                         green:(g / 255.0f)
                                           blue:(b / 255.0f)
                                         alpha:1.0f];
};

var makeColor = function(rgb) {
    return makrNSColor(rgb);
};