I currently retrieve information from my database with JSON by doing this in my php file, let's call it getJson.php:
<?php
include ("config.php");
$query = "SELECT id,title,text,image,date FROM posts";
$result = mysql_query($query) or die(mysql_error());
$num = mysql_num_rows($result);
$rows = array();
while ($r = mysql_fetch_assoc($result)){
$rows[] = $r;
}
echo json_encode($rows);
?>
Then in my application I retrieve the JSON representation by using:
NSURL *url = [NSURL URLWithString:kGETUrlPosts];
NSData *data = [NSData dataWithContentsOfURL:url];
NSError *error;
postsArray = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
I also have binary image data stored as a BLOB which I would like to retrieve. However I cannot JSON encode this binary data in JSON, can I ?
My second option would have been keeping a URL to my image in the image field and then just call
UIImage *img = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"www.myURL.com/MyPhotos/somephoto.png"]]];
Our Solution in 3 steps.
Step1. Create a dedicated php script that accepts a $_GET param 'imageId'
<?php
//Lets call this script as 'getImage.php'.
//This script should be publicly accessible
//Example format: http://www.yourdomain.com/getImage.php?imageId=2
include ("config.php");
$query = "SELECT image FROM posts WHERE id=" . mysql_real_escape_string($_GET['imageId']);
$result = mysql_query($query) or die(mysql_error());
$r = mysql_fetch_assoc($result);
//display the image
$im = imagecreatefromstring($r['image']);
if ($im !== false) {
// I assume you use only jpg
//You may have to modify this block if you use some othe image format
//visit: http://php.net/manual/en/function.imagejpeg.php
header('Content-Type: image/jpeg');
imagejpeg($im);
imagedestroy($im);
} else {
echo 'error.';
}
?>
Step2. Modify your getJson.php
<?php
include ("config.php");
//Notice the change in query.
$query = "SELECT id,title,text,date FROM posts";
$result = mysql_query($query) or die(mysql_error());
$num = mysql_num_rows($result);
$rows = array();
while ($r = mysql_fetch_assoc($result)){
//Please replace below url with your real server url.
$r['image'] = 'http://www.yourdomain.com/getImage.php?imageId=' . $r['id'];
$rows[] = $r;
}
echo json_encode($rows);
?>
Step3 - IOS end - showing the image
The image url is present in your repsponse array (i think postsArray). You just have to treat the image url in each row just like a normal image!
Notes: