How to edit an XML file in ios5.1 ?

Question

Hi,
I have an large xml file . I need to split it into 3 small ones .For reading the XML i am using NSXMLParser . How to write xml file ? If there is need of edit some tag , how to do it ?Please guide me ....
Thanks
Amiya

Answer 1

I don't know what your model is but if I assume a straighforward tree-structured model PresetInfo > Modality > Body, this code is the design pattern I usually use.  If you don't actually need to load a model, but instead just extract a specific data element, look at the XPath query in PresetInfo.parseXmlElement, and how I get attribute and element values in the other parseXmlElements.
The model interface.  I used arrays for the lists, if you need keyed access to list elements, you could use dictionaries.  The top-level class PresetInfo contains methods to read the XML from a file.
@interface ModelBase : NSObject
- (id)initWithXmlElement:(GDataXMLElement *)element;
- (void)parseXmlElement:(GDataXMLElement *)element;
@end
@interface PresetInfo : ModelBase
@property NSMutableArray *modalities;
- (id)initWithPath:(NSString *)path;
- (id)initWithXmlString:(NSString *)xmlString;
@end
@interface Modality : ModelBase
@property NSString *type;
@property NSMutableArray *bodies;
@end
@interface Body : ModelBase
@property NSString *part;
@property NSInteger ww;
@property NSInteger wl;
@end
The model implementation.
@implementation ModelBase
- (id)initWithXmlElement:(GDataXMLElement *)element
    if (self = [self init]) {
        [self parseXmlElement:element];
    return self;
- (void)parseXmlElement:(GDataXMLElement *)element {
    [NSException raise:NSInternalInconsistencyException format:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];  // Objective-C has no abstract methods
@end
@implementation PresetInfo
- (id)init
    if (self = [super init]) {
        self.modalities = [[NSMutableArray alloc] init];
    return self;
- (id)initWithPath:(NSString *)path
    NSError *error = nil;
    NSStringEncoding *usedEncoding = nil;
    NSString *xmlString = [NSString stringWithContentsOfFile:path usedEncoding:usedEncoding error:&error];
    if (!xmlString)
        NSLog(@"Error reading XML file: %@", [error localizedDescription]);
    return [self initWithXmlString:xmlString];
- (id)initWithXmlString:(NSString *)xmlString
    NSError *error = nil;
    GDataXMLDocument *xmlDoc = [[GDataXMLDocument alloc] initWithXMLString:xmlString  options:0 error:&error];
    if (!xmlDoc)
        NSLog(@"Error creating XML document: %@", [error localizedDescription]);
    return [self initWithXmlElement:xmlDoc.rootElement];
- (void)parseXmlElement:(GDataXMLElement *)element
    NSError *error = nil;
    NSArray *nodes = [element nodesForXPath:@"presetinfo/modality" error:&error];
    if (!nodes) {
        NSLog(@"Response not found: %@", [error localizedDescription]);
        return;
    for (GDataXMLElement *element in nodes)
        [self.modalities addObject:[[Modality alloc] initWithXmlElement:element]];
@end
@implementation Modality
- (id)init
    if (self = [super init]) {
        self.bodies = [[NSMutableArray alloc] init];
    return self;
- (void)parseXmlElement:(GDataXMLElement *)element {
    GDataXMLNode *node = [element attributeForName:@"type"];
    if (node) self.type = node.stringValue;
    NSArray *nodes = [element elementsForName:@"body"];
    for (GDataXMLElement *element in nodes)
        [self.bodies addObject:[[Body alloc] initWithXmlElement:element]];
@end
@implementation Body
- (void)parseXmlElement:(GDataXMLElement *)element {
    GDataXMLNode *node = [element attributeForName:@"PART"];
    if (node) self.part = node.stringValue;
    node = [element attributeForName:@"WW"];
    if (node) self.ww = [node.stringValue integerValue];
    node = [element attributeForName:@"WL"];
    if (node) self.wl = [node.stringValue integerValue];
@end
Example of loading your XML into the model and showing the data.  This assumes the containing class (for example a view controller) has a property PresetInfo *presetInfo and the XML you posted is in a file presetinfo.xml.
// load the XML into the model
NSString *path = [[NSBundle mainBundle] pathForResource:@"presetinfo" ofType:@"xml"];
self.presetInfo = [[PresetInfo alloc] initWithPath:path];
// verify the model loaded correctly
for (Modality *modality in self.presetInfo.modalities) {
    for (Body *body in modality.bodies) {
        NSLog(@"Modality Type = %@; Body Part = %@; WW = %d; WL = %d", modality.type, body.part, body.ww, body.wl);