URLParsing
Overview:
NSURL only goes so far in providing you access to chunks of a URL. If you need more parsing (like the parameters and query string etc) you can use these methods written by Jerry Krinock. http://goo.gl/OeSCu
Related Topics:
[Topic]
The Header
// NSSTRING METHODS WRITTEN BY JERRY KRINOCK [jerry]-[ieee]-[org]
@interface NSString (URIQuery)
// NSString has a method for decoding percent escapes but none for encoding // So, here they are: - (NSString)encodePercentEscapesPerRFC2396 ; - (NSString)encodePercentEscapesStrictlyPerRFC2396 ; // Decodes any existing percent escapes which should not be encoded per RFC 2396 sec. 2.4.3 // Encodes any characters which should be encoded per RFC 2396 sec. 2.4.3. - (NSString)encodePercentEscapesPerRFC2396ButNot:(NSString)butNot butAlso:(NSString)butAlso ;
// butNot and/or butAlso may be nil // I did an experiment to find out which ASCII characters are encoded, // by encoding a string with all the nonalphanumeric characters available on the // Macintosh keyboard, with and without the shift key down. There were fourteen: // ` # % ^ [ ] { } \ | " < > // You only see thirteen because the fourtheenth one is the space character, " ". // This agrees with the lists of "space" "delims" and "unwise" in by RFC 2396 sec. 2.4.3 // Also, I found that all of the non-ASCII characters available on the Macintosh // keyboard by using option or shift+option are also encoded. Some of these have // two bytes of unicode to encode, for example %C2%A4 for 0xC2A4
/! @brief Returns a string of the form "key0=value0&key1=value1&...". All keys and values are percent-escape encoded
@details For compatibility with POST, does not prepend a "?" All keys and all values must be NSString objects @param The dictionary of keys and values to be encoded into the string / + stringWithQueryDictionary:(NSDictionary)dictionary ;
/ Not sure how this is different than -stringByReplacingPercentEscapesUsingEncoding: Performing test in implementation to see if I can use that instead of this. / - (NSString)decodeAllPercentEscapes ;
/! @brief Assuming that the receiver is a query string of key=value pairs, of the form "key0=value0&key1=value1&...", with keys and values percent-escape encoded per RFC 2396, returns a dictionary of the keys and values.
@details Supports both ampersand "&" and semicolon ";" to delimit key-value pairs. The latter is recommended here: http://www.w3.org/TR/1998/REC-html40-19980424/appendix/notes.html#h-B.2.2 / - (NSDictionary)queryDictionaryUsingEncoding:(NSStringEncoding)encoding ;
@end
The Code
@implementation NSString (URIQuery)
- (NSString)encodePercentEscapesPerRFC2396 {
return (NSString)[(NSString)CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)self, NULL, NULL, kCFStringEncodingUTF8) autorelease] ;
}
- (NSString)encodePercentEscapesStrictlyPerRFC2396 {
CFStringRef decodedString = (CFStringRef)[self decodeAllPercentEscapes] ; // The above may return NULL if url contains invalid escape sequences like %E8me, %E8fe, %E800 or %E811, // because CFURLCreateStringByReplacingPercentEscapes() isn't smart enough to ignore them. CFStringRef recodedString = CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, decodedString, NULL, NULL, kCFStringEncodingUTF8); // And then, if decodedString is NULL, recodedString will be NULL too. // So, we recover from this rare but possible error by returning the original self // because it's "better than nothing". NSString answer = (recodedString != NULL) ? [(NSString)recodedString autorelease] : self ; // Note that if recodedString is NULL, we don't need to CFRelease() it. // Actually, CFRelease(NULL) causes a crash. That's kind of stupid, Apple. return answer ;
}
- (NSString)encodePercentEscapesPerRFC2396ButNot:(NSString)butNot butAlso:(NSString)butAlso {
return (NSString)[(NSString)CFURLCreateStringByAddingPercentEscapes( NULL, (CFStringRef)self, (CFStringRef)butNot, (CFStringRef)butAlso, kCFStringEncodingUTF8 ) autorelease] ;
}
+ stringWithQueryDictionary:(NSDictionary)dictionary {
NSMutableString string = [[[NSMutableString]] string] ; NSUInteger countdown = [dictionary count] ; NSString additionsToRFC2396 = @"+=;" ; for (NSString key in dictionary) { [string appendFormat:@"%@=%@", [key encodePercentEscapesPerRFC2396ButNot:nil butAlso:additionsToRFC2396], [[dictionary valueForKey:key] encodePercentEscapesPerRFC2396ButNot:nil butAlso:additionsToRFC2396] ] ; countdown-- ; if (countdown > 0) { [string appendString:@"&"] ; } } return [[[NSString]] stringWithString:string] ;
}
- (NSString)decodeAllPercentEscapes {
// Unfortunately, CFURLCreateStringByReplacingPercentEscapes() seems to only replace %[NUMBER] escapes NSString cfWay = (NSString)[(NSString)CFURLCreateStringByReplacingPercentEscapes(kCFAllocatorDefault, (CFStringRef)self, CFSTR("")) autorelease] ; NSString cocoaWay = [self stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding] ; if (![cfWay isEqualToString:cocoaWay]) { NSBeep() ; NSLog(@"[%@ %s]: CF and Cocoa different for %@", [self class], _cmd, self) ; }
return cfWay ;
}
- (NSDictionary)queryDictionaryUsingEncoding:(NSStringEncoding)encoding {
NSCharacterSet delimiterSet = [[[NSCharacterSet]] characterSetWithCharactersInString:@"&;"] ; NSMutableDictionary pairs = [[[NSMutableDictionary]] dictionary] ; NSScanner scanner = [[[[[NSScanner]] alloc] initWithString:self] autorelease] ; while (![scanner isAtEnd]) { NSString pairString ; [scanner scanUpToCharactersFromSet:delimiterSet intoString:&pairString] ; [scanner scanCharactersFromSet:delimiterSet intoString:NULL] ; NSArray kvPair = [pairString componentsSeparatedByString:@"="] ; if ([kvPair count] == 2) { NSString key = [[kvPair objectAtIndex:0] stringByReplacingPercentEscapesUsingEncoding:encoding] ; NSString value = [[kvPair objectAtIndex:1] stringByReplacingPercentEscapesUsingEncoding:encoding] ; [pairs setObject:value forKey:key] ; } }
return [[[NSDictionary]] dictionaryWithDictionary:pairs] ;
}
@end
