字符串编码与解码函数（UTF8）

字符串编码：

- (NSString *)urlEncode:(NSString *)oldString{  
     CFStringRef escaped = CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (__bridge CFStringRef)oldString, NULL, (CFStringRef)@"!*'();:@&=+$,/?%#[]", kCFStringEncodingUTF8);  
    return [NSString stringWithFormat:@"%@", escaped];  
}

字符串解码：

- (NSString *)urlDecode:(NSString *)oldString{  
    NSMutableString *unescaped = [NSMutableString stringWithString:oldString];  
    [unescaped replaceOccurrencesOfString:@"+" withString:@" " options:NSLiteralSearch range:NSMakeRange(0, [unescaped length])];  
    return [unescaped stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];  
}