Question

what is the standard pattern for transfering data using the tabbar?

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Solution

  1. Set up a local server on your computer (eventually this is what would be hosted on a website, etc...) To do this I suggest the following:

  2. Download XAMPP (http://www.apachefriends.org/en/xampp-macosx.html) follow instructions

    • Install in applications

    • Make htcdocs in XAMPP folder in applications read &write for all

    • Create a new folder titled Tutorials (in htcdocs)
    • Add a new php file called index.php
    • Write php code (NOTE THIS IS NOT SECURE, ONLY A VERY BASIC EXAMPLE)

in index.php write: //Very unsecure, but this finds the function parameter name

if(function_exists($_GET['f'])) {
    //If found, call the function with value as a parameter
   $_GET['f']($_GET['value']);
}
//actual function that takes in a number and finds the square of the number
function getLabel($number){
    //This variable response with parameter name is equal to the number times the number    
    $response['name']=$number*$number;
    //Return the data to the caller (in JSON encoded format)
    echo json_encode($response);
}

-Save and close your index.php file

  1. In Xcode create a new project, set it up with a text label that will display the result on the screen (very simple google a tutorial if you don't know how to do this)

Set up the connection in Xcode

Details and steps are explained in the .h and .m file (sorry not sure why the code portion here isn't showing as such)

//Step 1, add NSURLConnectionDataDelegate
    //.h
@interface ViewController : UIViewController<NSURLConnectionDataDelegate>
@property (strong, nonatomic) IBOutlet UILabel *answer;
@end

.m

#import "ViewController.h"

@interface ViewController ()
{//step 2 local data objects
    NSMutableData*webData;
    NSURLConnection*connection;

}
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    //Step 8 call (send) the request
    [self getData];
    // Do any additional setup after loading the view, typically from a nib.


    //NSDictionary*dict=[NSJSONSerialization se]
}
//Step 3 implement this method 
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
    [webData setLength:0];
}

//Step 4 append the connection data to your object
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    [webData appendData:data];
}

//Step 5 Process results from request (called automatically when the data arrives)
-(void)connectionDidFinishLoading:(NSURLConnection *)connection{
    //Main parse

    //Web data

    NSError*error;

    //Dictionary serialized (processed) using JSON (Way of encoding data from a web request)
    NSDictionary*data=[NSJSONSerialization JSONObjectWithData:webData options:0 error:&error];

    //If data is nil, then print error
    if (data==nil) {
        NSLog(@"%@",error);
    }

    //Print the data
    NSLog(@"%@",data);

    //Get the numerical result from the dictionary key name
    NSNumber*num=[data valueForKey:@"name"];

    //Convert number to string
    NSString*label=[num stringValue];

    //Set the label to this result
    _answer.text=label;

}
//Step 7, actually initialize the request
-(void)getData{
    //I will break this down as if it where a generic method
    //Connect to the index.php file via this URL


    //Localhost/tutorials is the XAMPP folder on your computer

    //index.php is the php file

    //getLabel(int number){}
    //?f=getLabel (calling this method in the php file)

    //number=900
    //&value=900 is the parameter
    NSURL*url=[NSURL URLWithString:@"http://localhost/tutorials/index.php?f=getLabel&value=900"];

    //In the php file it does number*number and returns the results

    //URL request
    NSURLRequest*request=[NSURLRequest requestWithURL:url];

    //Set the connection
    connection = [NSURLConnection connectionWithRequest:request delegate:self];

    if (connection) {
        webData=[[NSMutableData alloc]init];
    }

    //*****Results of this request are processed by step 5

}//Step 6, in case data connection fails
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
    NSLog(@"fail");

}
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end
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