I would like to pass multiple parameters from the iphone sdk to a server-side php which interfaces with a mySQL database.
i found some answers on how to do this, but i'm having a hard time figuring out how to include several parameters.
what i have right now is
- (IBAction)sendButtonPressed:(id)sender
{
NSString *urlstr = [[NSString alloc] initWithFormat:#"http://server.com/file.php?date=%d", theDate];
NSURL *url = [[NSURL alloc] initWithString:urlstr];
[urlstr release];
[url release];
}
which would work for 1 parameter, but what i'm looking for would be something like
http://server.com/file.php?date=value&time=value&category=value&tags=value&entry=value
how would i going about doing this?
The - initWithFormat method takes multiple arguments for the format string.
So you can do things like this:
NSString *urlstr = [[NSString alloc] initWithFormat:#"http://server.com/file.php?date=%d&second=%d&third=%d", theDate, 2, thirdIVar];
- initWithFormat works almost identically to printf() and it variants.
Here is some printf() examples http://stahlforce.com/dev/index.php?tool=csc02
Edit: Where are the variables nameField, tagsField, dreamEntry defined and set?
Unless they are NSStrings and defined in the #interface you can not uses them in this way.
I suggest hard coding some values for testing:
NSString *urlstr = [[NSString alloc] initWithFormat:#"http://server.com/file.php?date=%#&time=%#&name=%#&category=%d&tags=%#&entry=%#", nil, nil, #"Name", nil, #"Tags", #"Dream"];
Creating an NSURL doesn't open communications with a server. It's just a data structure for holding a URL. You want to read up on NSURLConnection.
Are all the variables you're passing in your format really numbers? %d is the placeholder for a number; %# is an object. It's very surprising to be passing nil if you're expecting a number, even for testing purposes. It'll "work" because nil is 0, but it suggests that these aren't really numbers.
Related
I'm new to iOS develoment, and I'm trying to write an app that can scrape a website (HTML). Scraping google is just an example - I'm planning on scraping something a bit more complex...
My code is as follows:
#import "KppleViewController.h"
#import "TFHpple.h"
#implementation KppleViewController
#synthesize theButton;
- (IBAction)buttonPressed:(UIButton *)sender {
NSLog(#"button Pressed");
NSURL *url = [NSURL URLWithString: #"http://www.google.com"];
NSData *htmlData = [NSData dataWithContentsOfURL: url];
TFHpple *xpathParse = [[TFHpple alloc] initWithHTMLData:htmlData];
NSArray *elements = [xpathParse searchWithXPathQuery:#"//h3"];
TFHppleElement *element = [elements objectAtIndex:0];
NSString *h3Tag = [element content];
NSLog(#"x",h3Tag);
}
The problem is that I get an error when I attempt to write to console (via NSLog) to see if anything worked. The error that I get is "Data argument not used by format string"
I've searched all over the internet, to no avail. If I comment out the NSLog to see if I my previous code is correct, I get an error about the variable immediately above the NSlog (h3Tag) declared but not being used.
Any help would be greatly appreciated...
I'm also open to any other methods of scraping HTML...
You're being confused by this line:
NSLog(#"x",h3Tag);
All this line does is log the string x. The second argument is completely unused. What you want is something like this:
NSLog(#"%#", h3Tag);
or perhaps a bit more descriptive:
NSLog(#"h3Tag: %#", h3Tag);
The token %# inside of the format string indicates that this is where the next argument will be printed. You may want to read up on the String Format Specifiers or on Formatting String Objects in general.
use
NSLog(#"%#", h3Tag);
or
NSLog(h3Tag);
NSLog(#"x = %#",h3Tag);
Above line prints the value of h3Tag.
For more help about NSLog refer link: [http://www.cocoadev.com/index.pl?NSLog]
I have this:
partenaire_lat = 48.8160525;
partenaire_lng = 2.3257800;
And obtain a NSString like this:
NSString *endPoint =[NSString stringWithFormat:#"%#,%#", partenaire_lat, partenaire_lng];
and after using this NSString in some context I get this stupid error:
Variable is not a CFString.
But if I create the NSString like this:
endPoint = #"48.8160525,2.3257800" it then works perfect!
For this error Variable is not a CFString I tried the following:
NSString *endPoint1 =[NSString stringWithFormat:#"%#,%#", partenaire_lat, partenaire_lng];
CFStringRef endPoint =(CFStringRef)endPoint1;
and tried to use endPoint but not working neither this way.Anyone any miraculous idea?Thx
EDIT:partenaire_lat and partenaire_lng are both NSString!!
You have
partenaire_lat = 48.8160525;
partenaire_lng = 2.3257800;
You keep saying that the two variables are NSStrings but you aren't assigning NSStrings to them. You need to assign NSString objects to NSString variables - they aren't created for you automatically.
So the answers which are telling you to use formatted strings are correct. You really should be doing it like this:
partenaire_lat = [[NSString stringWithFormat:#"%f", 48.8160525] retain];
partenaire_lng = [[NSString stringWithFormat:#"%f", 2.3257800] retain];
what are lat and lng? i'm assuming float or double..so you should use [NSString stringWithFormat:#"%f,%f", lat, lng]; (or however you want the floats to be formatted)
You code has several potential problems:
%# format specifier expects object parameter, while it looks like you pass plain float (I may be wrong here as there's not enough context to be sure). Change format to %f to fix your problem if that's really the case:
NSString *endPoint1 =[NSString stringWithFormat:#"%f,%f", partenaire_lat, partenaire_lng];
Your endPoint1 string is autoreleased and may become invalid outside of current scope if you don't retain it. So if you try to use your variable in another method you probably should retain it.
All you need to do
NSString *latStr=[[NSNumber numberWithFloat:partenaire_lat] stringValue];
NSString *lngStr=[[NSNumber numberWithFloat:partenaire_lng] stringValue];
and do whatever you want to do with these two string :)
In order to obtain URL, I usually follow this way.
NSString *userText = urlText.text;
NSURL *url = [NSURL URLWithString:userText];
Of coursely, urlText is linked with UITextField.
However, Recently, I saw this code in audioStreaming program.
(This is the program.)
NSString *escapedValue =
[(NSString *)CFURLCreateStringByAddingPercentEscapes(nil, (CFStringRef)downloadSourceField.text, NULL, NULL,
kCFStringEncodingUTF8) autorelease];
NSURL *url = [NSURL URLWithString:escapedValue];
downloadSourceField is linked with UITextField.
What is diffence between these two methodes?
When I replaced the second method (escapedValue = ~~~ ) with (escapedValue = downloadSourceField.text;), the program worked well.
Could you let me know what is difference?
And What is the best method to obtain URL for streaming?
The second method will percent-escape some characters which are typically not allowed in URLs. As an example, the space character is not allowed and will be encoded as %20. NSURL does not support passing a string containing a non-allowed character which has not been escaped to +URLWithString:, therefore passing the string through CFURLCreateStringByAddingPercentEscapes first will let you support such URLs.
interesting,
however, digging in the NSString docs you find these two functions:
- (NSString *)stringByReplacingPercentEscapesUsingEncoding:(NSStringEncoding)encoding
- (NSString *)stringByAddingPercentEscapesUsingEncoding:(NSStringEncoding)encoding
I think those are the "official" way of doing this
I am reading string data from a PLIST which I am using to create a JSON string (incidentally for use within Facebook Connect).
NSString *eventLink = [eventDictionary objectForKey:EVENT_FIND_OUT_MORE_KEY];
NSString *eventLinkEscaped = [eventLink stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSString *eventName = [eventDictionary objectForKey:EVENT_NAME_KEY];
NSString *eventDescription = [eventDictionary objectForKey:#"Description"];
NSString *eventImageAddress = [eventDictionary valueForKey:#"Image URL"];
if ([eventImageAddress length] == 0)
{
eventImageAddress = NO_EVENT_IMAGE_URL;
}
// Publish a story to the feed using the feed dialog
FBStreamDialog *facebookStreamDialog = [[[FBStreamDialog alloc] init] autorelease];
facebookStreamDialog.delegate = self;
facebookStreamDialog.userMessagePrompt = #"Publish to Facebook";
facebookStreamDialog.attachment =[NSString stringWithFormat: #"{\"name\":\"%#\",\"href\":\"%#\",\"description\":\"%#\",\"media\":[{\"type\":\"image\",\"src\":\"%#\",\"href\":\"%#\"}]}", eventName, eventLinkEscaped, eventDescription, eventImageAddress, eventLinkEscaped];
[facebookStreamDialog show];
All this works well, but certain event descriptions (4 out of approx. 150) the text that appears in the dialog is blank. I have found the obvious candidates, i.e., the description contains the " character for instance or the copyright symbol. My question is, is there an easy method call, such as stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding that will ensure that any dodgy characters are escaped or ignored?
Thanks in advance,
Dave
I don't think there is an easy way to escape the problem strings. If you need JSON support anywhere else in your code, consider using one of the existing JSON parsing/generator frameworks such as yajl-objc or SBJSON. Either of these will let you build your response as Foundation objects (NSArray/NSDictionary) and then call a single method to generate the appropriate JSON. Your code will be cleaner and you have the benefit that both of these frameworks are well-tested.
If just need to generate this one bit of JSON, your best bet is probably to manually walk over the input strings, replacing potential problem characters with the appropriately escaped versions. Is is not as bad as you might think. Take a look at the source for SBJsonWriter
I'm trying to send the contents of UITextView or UITextField as parameters to a php file
NSString *urlstr = [[NSString alloc] initWithFormat:#"http://server.com/file.php?name=%#&tags=%#&entry=%#",nameField.text, tagsField.text, dreamEntry.text];
When i log urlstr, the url format is ok just as long as the UITextView or UITextField don't contain spaces. How would i go about converting the spaces to %20 ?
edit
here is the code at present, which not only crashes but isn't encoding the url properly.
name=John Doe&tags=recurring nightmare&entry=Testing testing testing
is converted to
name=John -1844684964oe&tags=recurringightmare&entry=Testing 4.214929e-307sting -1.992836e+00sting
- (IBAction)sendButtonPressed:(id)sender
{
NSString *urlString = [[NSString alloc] initWithFormat:#"http://server.com/file.php?name=%#&tags=%#&entry=%#", nameField.text, tagsField.text, dreamEntry.text];
NSString *encodedString = [urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSURL *url = [[NSURL alloc] initWithString:encodedString];
NSLog(encodedString);
NSLog(urlString);
[urlString release];
[url release];
[encodedString release];
}
Actually, all of the previous answers contain at least some inaccuracies, which for many common values of user provided text in the TextFields would not correctly communicate with the server
stringByAddingPercentEscapesUsingEncoding: percent escapes all characters which are not valid URL characters. This method should applied once to the entire URL.
A previous answer claims that stringByAddingPercentEscapesUsingEncoding: works like the URL building classes in many scripting languages, where you should not apply it to the entire URL string, but it doesn't. Anyone can easily verify this by checking its output for unescaped &s and ?s. So it is fine to apply to the entire string, but it is not enough to apply to your 'dynamic' url content.
The previous answer is right in that you have to do some more work to the names and values that go into your CGI query string. Since CGI is specified by RFC3875, this is often referred to as RFC3875 percent escaping. It makes sure that your names and values don't contain characters that are valid URL characters but which are significant in other parts of the URL (;, ?, :, #, &, =, $, +, {, }, <, >, and ,)
However, it is very important to also finish by doing plain URL percent escapes on the full string to make sure that all characters in the string are valid URL characters. While you don't in your example, in general there could be characters in a 'static' part of the string which are not valid URL characters, so you do need to escape those as well.
Unfortunately, NSString doesn't give us the power to escape the RFC3875 significant characters so we have to dip down into CFString to do so. Obviously using CFString is a pain so I generally add a Category onto NSString like so:
#interface NSString (RFC3875)
- (NSString *)stringByAddingRFC3875PercentEscapesUsingEncoding:(NSStringEncoding)encoding;
#end
#implementation NSString (RFC3875)
- (NSString *)stringByAddingRFC3875PercentEscapesUsingEncoding:(NSStringEncoding)encoding {
CFStringEncoding cfEncoding = CFStringConvertNSStringEncodingToEncoding(encoding);
NSString *rfcEscaped = (NSString *)CFURLCreateStringByAddingPercentEscapes(
NULL,
(CFStringRef)self,
NULL,
(CFStringRef)#";/?:#&=$+{}<>,",
cfEncoding);
return [rfcEscaped autorelease];
}
#end
With this Category in place, the original problem could be correctly solved with the following:
NSString *urlEscapedBase = [#"http://server.com/file.php" stringByAddingPercentEscapesUsingEncoding:
NSUTF8StringEncoding];
NSString *rfcEscapedName = [nameField.text stringByAddingRFC3875PercentEscapesUsingEncoding:
NSUTF8StringEncoding];
NSString *rfcEscapedTags = [tagsField.text stringByAddingRFC3875PercentEscapesUsingEncoding:
NSUTF8StringEncoding];
NSString *rfcEscapedEntry = [dreamEntry.text stringByAddingRFC3875PercentEscapesUsingEncoding:
NSUTF8StringEncoding];
NSString *urlStr = [NSString stringWithFormat:#"%#?name=%#&tags=%#&entry=%#",
urlEscapedBase,
rfcEscapedName,
rfcEscapedTags,
rfcEscapedEntry];
NSURL *url = [NSURL URLWithString:urlStr];
This is a little variable heavy just be more clear. Also note that the variable list provided to stringWithFormat: should not be nil terminated. The format string describes the precise number of variables that should follow it. Also, technically the strings for query string names (name, tags, entry,..) should be run through stringByAddingPercentEscapesUsingEncoding: as a matter of course but in this small example we can easily see that they contain no invalid URL characters.
To see why the previous solutions are incorrect, imagine that the user input text in dreamEntry.text contains an &, which is not unlikely. With the previous solutions, all text following that character would be lost by the time the server got that text, since the unescaped ampersand would be interpreted by the server as ending the value portion of that query string pair.
You're not supposed to URL-escape the entire string, you're supposed to URL-escape the dynamic components. Try
NSString *urlStr = [NSString stringWithFormat:#"http://server.com/file.php?name=%#&tags=%#&entry=%#",
[nameField.text stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding],
[tagsField.text stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding],
[dreamEntry.text stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding],
nil];
NSURL *url = [NSURL URLWithString:urlStr];
The second issue with your code (and undoubtedly the reason for the odd printing) is you're passing the string directly to NSLog, so it's being treated as a format string. You need to use
NSLog(#"%#", encodedString);
instead. That will make it print as expected.
Edit: A third issue with your code is you're mixing autoreleased and owned objects, then releasing them all at the end. Go look at the 3 objects you create, and which you subsequently release later. One of them shouldn't be released later because it was produced by a method that did not start with the words alloc, copy, or new. Identifying the object in question is an exercise left to the reader.
You can take your URL and use:
NSString *urlStr = [[NSString alloc] initWithFormat:#"http://server.com/file.php?name=%#&tags=%#&entry=%#",nameField.text, tagsField.text, dreamEntry.text];
NSString *encStr = [urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];