Promise is an object, which promises the user to get back the values or do some task after performing the promised activity without hampering the main UI. The execution of the other activities will work as normal. So in single word we can say, it is asynchronous.
The JOIN method of the Promise works like a waiter in the restaurant, waiting for the whole order from a table from each person. We can club separate promise objects and join them together. Join ensures to perform a task after all the promise objects finished their execution.
Queries encountered on the above
On all the above, I encountered the query,
what will happen when any of the Promise gets an error ?
Will it able to club the output and wait for the promises ? OR it will quite the execution ? Etc. etc.
Few days ago I received a comment from one of the reader of my blog to show an example on CRUD (Create, Read, Update and Delete) with the database. So in this post we will explore the use of CRUD operation using SQLite database in PhoneGap application.
CRUD can be described as a process, which helps the user to add, view, search and modify the information inside the database.
Here are the basic steps which demonstrates CRUD operation.
Create or add new entries
Read, retrieve, search or view existing entries
Update, modify or edit existing entries
Delete, deactivate or destroy existing entries
Before doing any operation on database let’s initialize the database first, either using HTML5 local database concept or using SQLite plugin. Continue reading →
Xamarin provides a number of ways to save data in iOS using Local Storage. User preferences are generally stored in Library/Preferences/.
Xamarin iOs provides its built in mechanism i.e. instead of creating files directly in the directory it is suggested to use NSUserDefaults class to save data.
Description: NSUserDefaults class provides its own built in mechanisms to save float, double, integers, Boolean and URL data. To save a custom object it should be converted to NSData object using NSUserDefaults. Continue reading →
Windows Phone comes with a number of controls for display. Among them the Panorama Control is one the new controls for user interaction and display.
Panorama Control spans beyond the screen and helps user to chose from a number of panorama items. Each panorama item can consists of Grids, Stack Panels and other Phone controls. Image applied to Panorama as background spans across all the panorama items. Only one panorama item is visible at a time and user can make selection from it. A swipe gesture gives the next or previous Panorama item. Continue reading →
Alert dialog is a important part of any application. Conveying various information, error messages and even for taking confirmations from user can be done through alert dialog. Xamarin provides it’s own way of showing alert and conveying messages to the user.
Alerts in Xamarin are, an object of AlertDialog.Builder class, where AlertDialog is a subclass of Dialog class. Builder() is a method of AlertDialog class, which creates an alert dialog to display. We can add multiple buttons to this alert dialog. The builder takes the current context (Activity) and shows the Alert Box in the main thread(The UI thread). Continue reading →
Xamarin provides different layout for designing the user interface in Android.
Some common ones being used are Relative Layout, Linear Layout, Grid Layout, Table Layout, Frame Layout etc. Most of them are understandable from their name itself. Here we will discuss about how to design using Relative Layout in Xamarin for Android.
As the name suggests, Relative Layout mainly makes use of the controls present in the Designer and places controls relatively to each other. The most important aspect of this design being the First element placed inside the tag. The places itself depending on the properties set for the children in the Relative Layout.
For example: Continue reading →
I received a bug ticket from my client about the unusual behavior of my application UI. It was a problem which was occurring only in iOS7 only.
When the keyboard pops up in iPad devices running on iOS7 the web view of our app gets shrink (app development using Phonegap).
Solution that works for me : This problem can be solved in few steps.
We need to go to Config.xml and inside the preference tag just need to set the value of KeyboardShrinksView to false.
While developing a PhoneGap application, I got a new requirement to add an event to native calendar from the application. So that user can get aware of the details of the event from native calendar.
To implement the same, I goggled for while and found a nice and interesting plugin which is very easy to integrate and works with PhoneGap smoothly. It allows the user to add the event to calendar of that device. Here are the steps bellow which will guide to integrate the calendar plugin in PhoneGap iOS application.
To control the synchronous or asynchronous flow, there may be more methods but we will do this by multiple callback mechanism using deferred and promise object.
In order to use this mechanism first we need to have an understanding of deferred and promise object.
Here we will use a promise with a deferred object.
A promise is a placeholder for a result, which is initially unknown. While a deferred represents the computation that results in the value. Every deferred has a promise, which functions as a proxy for the future result.
A promise is a value returned by an asynchronous function, but a deferred can be resolved or rejected by its caller which separates the promise from the resolver. Continue reading →
For offline storage in PhoneGap application, we can use local storage or storage API. But there are some limitations of this storage mechanism. So here we will discuss on creating local database with larger storage limits with the help of SQLite plugin.
To overcome the limitations, we can use the SQLite plugin which is very easy to integrate. Here are the steps below which will guide to integrate the SQLite plugin in PhoneGap iOS application.
1. Download the SQLite plugin from github by using this url.
2. The plugins are inside Cordova-SQLitePlugin / src / ios /. Let’s drag the SQLitePlugin.h and SQLitePlugin.m files into the Plugins directory in Xcode and choose the “Create folder references for any added folders” option while adding reference. Continue reading →