Objective-C urlEncode urlDecode

@interface NSString (stringByDecodingURLFormat)

- (NSString *)stringByDecodingURLFormat;
- (NSString*)stringByURLEncodingStringParameter;
@end

@implementation NSString(stringByDecodingURLFormat)

- (NSString *)stringByDecodingURLFormat
{
    NSString *result = [(NSString *)self stringByReplacingOccurrencesOfString:@"+" withString:@" "];
    result = [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    return result;
}

//encode
- (NSString*)stringByURLEncodingStringParameter
{

    NSString *resultStr = self;

    CFStringRef originalString = (__bridge CFStringRef) self;
    CFStringRef leaveUnescaped = CFSTR(" ");
    CFStringRef forceEscaped = CFSTR("!*'();:@&=+$,/?%#[]");

    CFStringRef escapedStr;
    escapedStr = CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                                         originalString,
                                                         leaveUnescaped,
                                                         forceEscaped,
                                                         kCFStringEncodingUTF8);

    if( escapedStr )
    {
        NSMutableString *mutableStr = [NSMutableString stringWithString:(__bridge NSString *)escapedStr];
        CFRelease(escapedStr);
        [mutableStr replaceOccurrencesOfString:@" "
                                    withString:@"%20"
                                       options:
                                         range:NSMakeRange(, [mutableStr length])];
        resultStr = mutableStr;
    }
    return resultStr;
}
@end

把以上代码假如到NSString 的分类就可以直接使用