Question

I syncing the data on my website to my app, I’m using NSXMLParser to do this. The problem is I have all the fields on my database defined as Strings. The sync process works fine when everything is a string, but this is causing me heartache further down the line when I try and use this data for other purposes.

Can anyone help me with defining my fields with the correct data types for the sync process, code below:

.m

// Array for WORKOUT.
    NSMutableString *currentID, *currentUserID, *currentWalkID, *currentDate, *currentDistance, *currentRepeats, *currentType, *currentIntensity,
    *currentComments, *currentTime, *currentWeight, *currentHeight;

I know its something to do with this NSMutableString, obviously everything is defined as a string.

.h

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{           
    currentElement = [elementName copy];

    // Check for the WORKOUT details in the XML feed.
    if ([elementName isEqualToString:@"workout"]) 
    {
        // clear out our workout item caches...
        item = [[NSMutableDictionary alloc] init];
        currentID = [[NSMutableString alloc] init];
        currentUserID = [[NSMutableString alloc] init];
        currentWalkID = [[NSMutableString alloc] init];
        currentDate = [[NSMutableString alloc] init];
        currentDistance = [[NSMutableString alloc] init];
        currentRepeats = [[NSMutableString alloc] init];
        currentType = [[NSMutableString alloc] init];
        currentIntensity = [[NSMutableString alloc] init];
        currentComments = [[NSMutableString alloc] init];
        currentTime = [[NSMutableString alloc] init];
        currentWeight = [[NSMutableString alloc] init];
        currentHeight = [[NSMutableString alloc] init];
    }
}   


- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{     
    if ([elementName isEqualToString:@"workout"]) 
    {
        Workout *newWorkout = [NSEntityDescription insertNewObjectForEntityForName:@"Workout" inManagedObjectContext: self.managedObjectContext];

        // save values to an item, then store that item into the array...
        [item setObject:currentID forKey:@"workout_id"];
        [item setObject:currentUserID forKey:@"workout_user_id"];
        [item setObject:currentWalkID forKey:@"workout_walk_id"];
        [item setObject:currentDate forKey:@"workout_date"];
        [item setObject:currentDistance forKey:@"workout_distance"];
        [item setObject:currentRepeats forKey:@"workout_repeats"];
        [item setObject:currentType forKey:@"workout_type"];
        [item setObject:currentIntensity forKey:@"workout_intensity"];
        [item setObject:currentComments forKey:@"workout_comments"];
        [item setObject:currentTime forKey:@"workout_time"];
        [item setObject:currentWeight forKey:@"workout_weight"];
        [item setObject:currentHeight forKey:@"workout_height"];

        newWorkout.workout_id = currentID;
        newWorkout.workout_user_id = currentUserID;
        newWorkout.workout_walk_id = currentWalkID;
        newWorkout.workout_date = currentDate;
        newWorkout.workout_distance = currentDistance;
        newWorkout.workout_repeats = currentRepeats;
        newWorkout.workout_type = currentType;
        newWorkout.workout_intensity = currentIntensity;
        newWorkout.workout_comments = currentComments;
        newWorkout.workout_time = currentTime;
        newWorkout.workout_weight = currentWeight;
        newWorkout.workout_height = currentHeight;
        [self.workoutArray addObject:newWorkout];
    }
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
    // save the characters for the current item...
    if ([currentElement isEqualToString:@"workout_id"]) {
        [currentID appendString:string];
    } else if ([currentElement isEqualToString:@"workout_user_id"]) {
        [currentUserID appendString:string];
    } else if ([currentElement isEqualToString:@"workout_walk_id"]) {
        [currentWalkID appendString:string];
    } else if ([currentElement isEqualToString:@"workout_date"]) {
        [currentDate appendString:string];
    } else if ([currentElement isEqualToString:@"workout_distance"]) {
        [currentDistance appendString:string];
    } else if ([currentElement isEqualToString:@"workout_repeats"]) {
        [currentRepeats appendString:string];
    } else if ([currentElement isEqualToString:@"workout_type"]) {
        [currentType appendString:string];
    } else if ([currentElement isEqualToString:@"workout_intensity"]) {
        [currentIntensity appendString:string];
    } else if ([currentElement isEqualToString:@"workout_comments"]) {
        [currentComments appendString:string];
    } else if ([currentElement isEqualToString:@"workout_time"]) {
        [currentTime appendString:string];
    } else if ([currentElement isEqualToString:@"workout_weight"]) {
        [currentWeight appendString:string];
    } else if ([currentElement isEqualToString:@"workout_height"]) {
        [currentHeight appendString:string];
} 

Answer 1

XML can only carry strings. Wheather it’s an element’s inner text or the value of an attribute, in the end everything is just a string.

If you want to send anything other via XML, the sending side has to encode it in a string and the receiving side has to decode the string. For that to work both sides have to agree on a format, for Example for an Integer value one possibility is to encode 125 as “125”, or a float 2.5 as “2.5”. If you are using this format for your numbers you can decode them by using the integerValue and floatValue of NSString.

float test = [@"2.5" floatValue];

There are some standard formats defined in xsd, that you could use, but that will not help you decode them, if you don’t have a parser that does this for you. (NSXMLParser is no such)
If you are using other Formats look at NSScanner. For dates and time you would like to look at NSDateFormatter.

If you need help converting please post the format you are using, that is an excerpt of your XML.