application-management.md

nav-title	title	description	position
Application Management in NativeScript	App: Management	Learn how to manage the life cycle of NativeScript applications from application start to storing user-defined settings.	4

Application Management

The application module lets you manage the life cycle of your NativeScript apps from starting the application to storing user-defined settings.

• Start Application
• Use Application Events
• Android Activity Events
• iOS UIApplicationDelegate
• Persist and Restore Application Settings

Start Application

This method is required only for iOS applications.

IMPORTANT: You must call the start method of the application module after the module initialization. Any code after the start call will not be executed.

Example

/*
iOS calls UIApplication and triggers the application main event loop.
*/

var application = require("application");
application.mainModule = "main-page";
application.start();

/*
iOS calls UIApplication and triggers the application main event loop.
*/

import application = require("application");
application.mainModule = "main-page";
application.start();

Use Application Events

NativeScript applications have the following life cycle events.

• launch: This event is raised when application launch.
• suspend: This event is raised when the application is suspended.
• resume: This event is raised when the application is resumed after it has been suspended.
• exit: This event is raised when the application is about to exit.
• lowMemory: This event is raised when the memory on the target device is low.
• uncaughtError: This event is raised when an uncaught application error is present.

Example

var application = require("application");
application.mainModule = "main-page";

application.on(application.launchEvent, function (args) {
    if (args.android) {
        // For Android applications, args.android is an android.content.Intent class.
        console.log("Launched Android application with the following intent: " + args.android + ".");
    } else if (args.ios !== undefined) {
        // For iOS applications, args.ios is NSDictionary (launchOptions).
        console.log("Launched iOS application with options: " + args.ios);
    }
});

application.on(application.suspendEvent, function (args) {
    if (args.android) {
        // For Android applications, args.android is an android activity class.
        console.log("Activity: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is UIApplication.
        console.log("UIApplication: " + args.ios);
    }
});

application.on(application.resumeEvent, function (args) {
    if (args.android) {
        // For Android applications, args.android is an android activity class.
        console.log("Activity: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is UIApplication.
        console.log("UIApplication: " + args.ios);
    }
});

application.on(application.exitEvent, function (args) {
    if (args.android) {
        // For Android applications, args.android is an android activity class.
        console.log("Activity: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is UIApplication.
        console.log("UIApplication: " + args.ios);
    }
});

application.on(application.lowMemoryEvent, function (args) {
    if (args.android) {
        // For Android applications, args.android is an android activity class.
        console.log("Activity: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is UIApplication.
        console.log("UIApplication: " + args.ios);
    }
});

application.on(application.uncaughtErrorEvent, function (args) {
    if (args.android) {
        // For Android applications, args.android is an NativeScriptError.
        console.log("NativeScriptError: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is NativeScriptError.
        console.log("NativeScriptError: " + args.ios);
    }
});

application.start();

import application = require("application");
application.mainModule = "main-page";
application.on(application.launchEvent, function (args: application.ApplicationEventData) {
    if (args.android) {
        // For Android applications, args.android is an android.content.Intent class.
        console.log("Launched Android application with the following intent: " + args.android + ".");
    } else if (args.ios !== undefined) {
        // For iOS applications, args.ios is NSDictionary (launchOptions).
        console.log("Launched iOS application with options: " + args.ios);
    }
});

application.on(application.suspendEvent, function (args: application.ApplicationEventData) {
    if (args.android) {
        // For Android applications, args.android is an android activity class.
        console.log("Activity: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is UIApplication.
        console.log("UIApplication: " + args.ios);
    }
});

application.on(application.resumeEvent, function (args: application.ApplicationEventData) {
    if (args.android) {
        // For Android applications, args.android is an android activity class.
        console.log("Activity: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is UIApplication.
        console.log("UIApplication: " + args.ios);
    }
});

application.on(application.exitEvent, function (args: application.ApplicationEventData) {
    if (args.android) {
        // For Android applications, args.android is an android activity class.
        console.log("Activity: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is UIApplication.
        console.log("UIApplication: " + args.ios);
    }
});

application.on(application.lowMemoryEvent, function (args: application.ApplicationEventData) {
    if (args.android) {
        // For Android applications, args.android is an android activity class.
        console.log("Activity: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is UIApplication.
        console.log("UIApplication: " + args.ios);
    }
});

application.on(application.uncaughtErrorEvent, function (args: application.ApplicationEventData) {
    if (args.android) {
        // For Android applications, args.android is an NativeScriptError.
        console.log("NativeScriptError: " + args.android);
    } else if (args.ios) {
        // For iOS applications, args.ios is NativeScriptError.
        console.log("NativeScriptError: " + args.ios);
    }
});
application.start();

Android Activity Events

NativeScript applications have the following Android specific activity events:

• activityCreated: This event is raised when activity is created.
• activityDestroyed: This event is raised when activity is destroyed.
• activityStarted: This event is raised when activity is started.
• activityPaused: This event is raised when activity is paused.
• activityResumed: This event is raised when activity is resumed.
• activityStopped: This event is raised when activity is stopped.
• saveActivityState: This event is raised to retrieve per-instance state from an activity before being killed so that the state can be restored.
• activityResult: This event is raised when an activity you launched exits, giving you the requestCode you started it with, the resultCode it returned, and any additional data from it.
• activityBackPressed: This event is raised when the activity has detected the user's press of the back key.

Example

var application = require("application");

application.mainModule = "app/mainPage";

if (application.android) {
    application.android.on(application.AndroidApplication.activityCreatedEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity + ", Bundle: " + args.bundle);
    });
    
    application.android.on(application.AndroidApplication.activityDestroyedEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });
    
    application.android.on(application.AndroidApplication.activityStartedEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });
    
    application.android.on(application.AndroidApplication.activityPausedEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });
    
    application.android.on(application.AndroidApplication.activityResumedEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });
    
    application.android.on(application.AndroidApplication.activityStoppedEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });
    
    application.android.on(application.AndroidApplication.saveActivityStateEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity + ", Bundle: " + args.bundle);
    });
    
    application.android.on(application.AndroidApplication.activityResultEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity +
            ", requestCode: " + args.requestCode + ", resultCode: " + args.resultCode + ", Intent: " + args.intent);
    });
    
    application.android.on(application.AndroidApplication.activityBackPressedEvent, function (args) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
        // Set args.cancel = true to cancel back navigation and do something custom.
    });
}

application.start();

import application = require("application");
application.mainModule = "app/mainPage";

// Android activity events
if (application.android) {
    application.android.on(application.AndroidApplication.activityCreatedEvent, function (args: application.AndroidActivityBundleEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity + ", Bundle: " + args.bundle);
    });

    application.android.on(application.AndroidApplication.activityDestroyedEvent, function (args: application.AndroidActivityEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });

    application.android.on(application.AndroidApplication.activityStartedEvent, function (args: application.AndroidActivityEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });

    application.android.on(application.AndroidApplication.activityPausedEvent, function (args: application.AndroidActivityEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });

    application.android.on(application.AndroidApplication.activityResumedEvent, function (args: application.AndroidActivityEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });

    application.android.on(application.AndroidApplication.activityStoppedEvent, function (args: application.AndroidActivityEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
    });

    application.android.on(application.AndroidApplication.saveActivityStateEvent, function (args: application.AndroidActivityBundleEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity + ", Bundle: " + args.bundle);
    });

    application.android.on(application.AndroidApplication.activityResultEvent, function (args: application.AndroidActivityResultEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity +
            ", requestCode: " + args.requestCode + ", resultCode: " + args.resultCode + ", Intent: " + args.intent);
    });

    application.android.on(application.AndroidApplication.activityBackPressedEvent, function (args: application.AndroidActivityBackPressedEventData) {
        console.log("Event: " + args.eventName + ", Activity: " + args.activity);
        // Set args.cancel = true to cancel back navigation and do something custom.
    });
}

application.start();

iOS UIApplicationDelegate

Since NativeScript 1.3 you can specify custom UIApplicationDelegate for the iOS application:

Example

var application = require("application");
var MyDelegate = (function (_super) {
    __extends(MyDelegate, _super);
    function MyDelegate() {
        _super.apply(this, arguments);
    }
    MyDelegate.prototype.applicationDidFinishLaunchingWithOptions = function (application, launchOptions) {
        console.log("applicationWillFinishLaunchingWithOptions: " + launchOptions);
        return true;
    };
    MyDelegate.prototype.applicationDidBecomeActive = function (application) {
        console.log("applicationDidBecomeActive: " + application);
    };
    MyDelegate.ObjCProtocols = [UIApplicationDelegate];
    return MyDelegate;
})(UIResponder);
application.ios.delegate = MyDelegate;
application.start();

import application = require("application");
class MyDelegate extends UIResponder implements UIApplicationDelegate {
    public static ObjCProtocols = [UIApplicationDelegate];

    applicationDidFinishLaunchingWithOptions(application: UIApplication, launchOptions: NSDictionary): boolean {
        console.log("applicationWillFinishLaunchingWithOptions: " + launchOptions)

        return true;
    }

    applicationDidBecomeActive(application: UIApplication): void {
        console.log("applicationDidBecomeActive: " + application)
    }
}
application.ios.delegate = MyDelegate;
application.start();

Persist and Restore Application Settings

To persist user-defined settings, you need to use the application-settings module. The application-settings module is a static singleton hash table that stores key-value pairs for the application.

The getter methods have two parameters: a key and an optional default value to return if the specified key does not exist. The setter methods have two required parameters: a key and value.

Example

var applicationSettings = require("application-settings");
// Event handler for Page "loaded" event attached in main-page.xml.
function pageLoaded(args) {
    applicationSettings.setString("Name", "John Doe");
    console.log(applicationSettings.getString("Name")); // Prints "John Doe".
    applicationSettings.setBoolean("Married", false);
    console.log(applicationSettings.getBoolean("Married")); // Prints false.
    applicationSettings.setNumber("Age", 42);
    console.log(applicationSettings.getNumber("Age")); // Prints 42.
    console.log(applicationSettings.hasKey("Name")); // Prints true.
    applicationSettings.remove("Name"); // Removes the Name entry.
    console.log(applicationSettings.hasKey("Name")); // Prints false.
}
exports.pageLoaded = pageLoaded;

import observable = require("data/observable");
import applicationSettings = require("application-settings");
// Event handler for Page "loaded" event attached in main-page.xml.
export function pageLoaded(args: observable.EventData) {
    applicationSettings.setString("Name", "John Doe");
    console.log(applicationSettings.getString("Name"));// Prints "John Doe".
    applicationSettings.setBoolean("Married", false);
    console.log(applicationSettings.getBoolean("Married"));// Prints false.
    applicationSettings.setNumber("Age", 42);
    console.log(applicationSettings.getNumber("Age"));// Prints 42.
    console.log(applicationSettings.hasKey("Name"));// Prints true.
    applicationSettings.remove("Name");// Removes the Name entry.
    console.log(applicationSettings.hasKey("Name"));// Prints false.
}