Sencha - More about Sencha Touch 2 Framework

Hello everyone,

   As I did mention last weekend, this weekend I am going to show you how to run your app using Sencha Touch Framework. Sencha Touch is a user interface (UI) JavaScript library, or we can say a framework, specifically built for the Mobile Web. You can use it to develop user interfaces for mobile web applications that look and feel like native applications on supported mobile devices. That's the beauty of it.

Sencha Touch is fully based on web standards such as HTML5, CSS3 and JavaScript.  The magnificent  of Sencha Touch is this framework enable developers to quickly and easily create HTML5 based mobile apps that work on Android, iOS, Windows, Tizen and BlackBerry devices, and produce a native-app-like experience inside a browser.

So, today I'm gonna show you the step-by-step to run Sencha via browser or via Apache Cordova, if you will.

Let' move it on:

Step 1: Go to https://www.sencha.com/ and download your Sencha Touch Framework as below:

You Should get a folder like this. The release that I am using is touch-2.4.2.

Step 2: I do recommend you to download the Sencha Cmd library, install and add in in your .bash_profile to make it easy to execute Sencha commands as I'm gonna show here today.

Go to https://www.sencha.com/products/extjs/cmd-download/ and download it to you machine.

Step 3: Install Sencha Cmd as it's showed below and check if there is any upgrade pending doing the commands I am showing on the next pictures. Eg: Sencha upgrade --check

Step4: Here it's the good and easy part to launch your Sencha App - Go to your App folder -Run these 3 commands to make your app a Sencha app:

sencha generate app -ext MyApp /path/to/MyApp


Note:If your app is not upgraded for the latest sencha version you should get this issue below when running generate command. The solution is just run as It shows below sencha app upgrade command.

sencha -sdk /path/to/ext generate app MyApp /path/to/MyApp

sencha app build

Then run sencha diag show  to see what sencha framework can get from your app that was already built based on Sencha.

Step 5: Now you should be able to launch your app running sencha app run command.

You should be able to get your app running over your browser, eg: http://localhost:1841/yourapp

NOTE: If you get any issue on running part of your app, just run sencha app watch command as below.

Now, that you have your Sencha app running fine, I want to tell you the good thing. We can run it from Apache cordova as well. So, let's see how it goes:

Step7 - Run the command sencha cordova init to initialize cordova folder over your sencha app project folder.

You will see that you have a folder for cordova inside of your app folder as I am showing below:

So, Apache Cordova requires you to add the platform that you want to launch your emulator. In this example is IOS. Note: You must run cordova platform add ios under the cordova folder that was created during sencha cordova initialization.

Don't forget to replace the files in cordova to make it part of your previous sencha app, eg:index.html and others.

type: cordova run

then have fun using cordova emulator. If you get stuck with cordova, you can see more about it on my previous blog related of cordova last year:

Apache Cordova Debugging Tools

Apache cordova How to Install

Happy coding,

Thiago Leoncio.

IOS - Maintaining a Block in Memory

IOS - Maintaining a Block in Memory

In Objective-C extension/block specification - "All Blocks are constructed to be Objective-C objects regardless of whether the Objective-C runtime is operational in the program or not. ", and they have the same memory layout. This consists primarily of its captured variables. Specifically for blocks the actual code is not stored in the memory but in a different part of the memory(text) with the rest of the executable code on your app.
When a block is created, the data associated with it are stored in the stack, including variables in its scope that it has taken a snapshot of. (The stack is a temporary memory that, in the form of a stack frame for the currently executing C function, stores information needed for executing that function--function parameters, local variables, and control information.)
When objective-c block goes out of scope, this memory ‘in place’ is subject to reallocation and then the block will be no longer valid.
If a block is used in the parameter of a method that is synchronous--that is, the code calling the block waits for the method to perform its computations before going on--there is no problem. The block will continue to be in scope, and its stack frame will still be there and available to the method being called.
If the method is asynchronous, however, the call of the method only starts its computation, which continues after the return of the method--there is a potential problem. The memory for the block may be overwritten before the code in the block executes. To avoid this problem it is common practice for an asynchronous method to copy the block from the stack to the heap by performing a copy operation. (The heap is the much larger and more permanent memory that contains segments of memory that the program can request.)
If it is otherwise desired to execute the block outside the scope it was created in, the block also needs to be copied to heap memory.

So, now let's see a block copy:

A block can be copied by sending a copy message to the block.

    void (^simplestThiagoBlock) (void);
    simplestBlock = ^{
         NSLog(@"Hi, I'm a Thiago’s block.");
 
    };
    [simplestThiagoBlock copy];

Please, understand that copying the block to the heap makes it subject to reference counting. If manual reference counting is used, the block should be released when no longer needed. So, keep this in mind in future.
In general, it is rare that you will need to copy a block. The first copy will move the block from the stack to the heap. Successive copies do nothing then only increasing the retain count. If you need to make an actual copy of a block, better you will need to recreate it.

Happy coding,
Thiago Leoncio.