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copied!<p>I had reason to write some extensions for this behavior that might come in handy. First the header:</p> <pre><code>#import <Foundation/Foundation.h> @interface NSString (XQueryComponents) - (NSString *)stringByDecodingURLFormat; - (NSString *)stringByEncodingURLFormat; - (NSMutableDictionary *)dictionaryFromQueryComponents; @end @interface NSURL (XQueryComponents) - (NSMutableDictionary *)queryComponents; @end @interface NSDictionary (XQueryComponents) - (NSString *)stringFromQueryComponents; @end </code></pre> <p>These methods extend NSString, NSURL, and NSDictionary, to allow you to convert to and from query components strings and dictionary objects containing the results.</p> <p>Now the related .m code:</p> <pre><code>#import "XQueryComponents.h" @implementation NSString (XQueryComponents) - (NSString *)stringByDecodingURLFormat { NSString *result = [self stringByReplacingOccurrencesOfString:@"+" withString:@" "]; result = [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; return result; } - (NSString *)stringByEncodingURLFormat { NSString *result = [self stringByReplacingOccurrencesOfString:@" " withString:@"+"]; result = [result stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; return result; } - (NSMutableDictionary *)dictionaryFromQueryComponents { NSMutableDictionary *queryComponents = [NSMutableDictionary dictionary]; for(NSString *keyValuePairString in [self componentsSeparatedByString:@"&"]) { NSArray *keyValuePairArray = [keyValuePairString componentsSeparatedByString:@"="]; if ([keyValuePairArray count] < 2) continue; // Verify that there is at least one key, and at least one value. Ignore extra = signs NSString *key = [[keyValuePairArray objectAtIndex:0] stringByDecodingURLFormat]; NSString *value = [[keyValuePairArray objectAtIndex:1] stringByDecodingURLFormat]; NSMutableArray *results = [queryComponents objectForKey:key]; // URL spec says that multiple values are allowed per key if(!results) // First object { results = [NSMutableArray arrayWithCapacity:1]; [queryComponents setObject:results forKey:key]; } [results addObject:value]; } return queryComponents; } @end @implementation NSURL (XQueryComponents) - (NSMutableDictionary *)queryComponents { return [[self query] dictionaryFromQueryComponents]; } @end @implementation NSDictionary (XQueryComponents) - (NSString *)stringFromQueryComponents { NSString *result = nil; for(__strong NSString *key in [self allKeys]) { key = [key stringByEncodingURLFormat]; NSArray *allValues = [self objectForKey:key]; if([allValues isKindOfClass:[NSArray class]]) for(__strong NSString *value in allValues) { value = [[value description] stringByEncodingURLFormat]; if(!result) result = [NSString stringWithFormat:@"%@=%@",key,value]; else result = [result stringByAppendingFormat:@"&%@=%@",key,value]; } else { NSString *value = [[allValues description] stringByEncodingURLFormat]; if(!result) result = [NSString stringWithFormat:@"%@=%@",key,value]; else result = [result stringByAppendingFormat:@"&%@=%@",key,value]; } } return result; } @end </code></pre>

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